In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, overclocking is the practice of increasing the
clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
of a computer to exceed that certified by the manufacturer. Commonly, operating
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
is also increased to maintain a component's operational stability at accelerated speeds.
Semiconductor devices operated at higher frequencies and voltages increase power consumption and heat. An overclocked device may be unreliable or fail completely if the additional heat load is not removed or power delivery components cannot meet increased power demands. Many device
warranties
In contract law, a warranty is a promise which is not a condition of the contract or an innominate term: (1) it is a term "not going to the root of the contract",Hogg M. (2011). ''Promises and Contract Law: Comparative Perspectives''p. 48 Cambri ...
state that overclocking or over-specification voids any warranty, however there are an increasing number of manufacturers that will allow overclocking as long as performed (relatively) safely.
Overview
The purpose of overclocking is to increase the operating speed of a given component. Normally, on modern systems, the target of overclocking is increasing the performance of a major chip or subsystem, such as the main processor or graphics controller, but other components, such as system memory (
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
) or
system buses (generally on the
motherboard), are commonly involved. The trade-offs are an increase in power consumption (heat), fan noise (cooling), and shortened lifespan for the targeted components. Most components are designed with a margin of safety to deal with operating conditions outside of a manufacturer's control; examples are ambient temperature and fluctuations in operating voltage. Overclocking techniques in general aim to trade this safety margin by setting the device to run in the higher end of the margin, with the understanding that temperature and voltage must be more strictly monitored and controlled by the user. Examples are that operating temperature would need to be more strictly controlled with increased cooling, as the part will be less tolerant of increased temperatures at the higher speeds. Also base operating voltage may be increased to compensate for unexpected voltage drops and to strengthen signalling and timing signals, as low-voltage excursions are more likely to cause malfunctions at higher operating speeds.
While most modern devices are fairly tolerant of overclocking, all devices have finite limits. Generally for any given voltage most parts will have a maximum "stable" speed where they still operate correctly. Past this speed, the device starts giving incorrect results, which can cause malfunctions and sporadic behavior in any system depending on it. While in a PC context the usual result is a system crash, more subtle errors can go undetected, which over a long enough time can give unpleasant surprises such as
data corruption
In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted. ...
(incorrectly calculated results, or worse ''writing to storage'' incorrectly) or the system failing only during certain specific tasks (general usage such as internet browsing and
word processing
A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...
appear fine, but any application wanting advanced graphics crashes the system).
At this point, an increase in operating voltage of a part may allow more headroom for further increases in clock speed, but the increased voltage can also significantly increase heat output, as well as shorten the lifespan further. At some point, there will be a limit imposed by the ability to supply the device with sufficient power, the user's ability to cool the part, and the device's own maximum voltage tolerance before it achieves
destructive failure. Overzealous use of voltage or inadequate cooling can rapidly degrade a device's performance to the point of failure, or in extreme cases outright
destroy it.
The speed gained by overclocking depends largely upon the applications and workloads being run on the system, and what components are being overclocked by the user;
benchmark
Benchmark may refer to:
Business and economics
* Benchmarking, evaluating performance within organizations
* Benchmark price
* Benchmark (crude oil), oil-specific practices
Science and technology
* Benchmark (surveying), a point of known elevati ...
s for different purposes are published.
Underclocking
Conversely, the primary goal of
underclocking
Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified. Underclocking is used to reduce a computer's power consumption, increase battery life, red ...
is to reduce power consumption and the resultant heat generation of a device, with the trade-offs being lower clock speeds and reductions in performance. Reducing the cooling requirements needed to keep hardware at a given operational temperature has knock-on benefits such as lowering the number and speed of fans to allow
quieter operation, and in mobile devices increase the length of battery life per charge. Some manufacturers underclock components of battery-powered equipment to improve battery life, or implement systems that detect when a device is operating under battery power and reduce clock frequency.
Underclocking and undervolting would be attempted on a desktop system to have it operate silently (such as for a home entertainment center) while potentially offering higher performance than currently offered by low-voltage processor offerings. This would use a "standard-voltage" part and attempt to run with lower voltages (while attempting to keep the desktop speeds) to meet an acceptable performance/noise target for the build. This was also attractive as using a "standard voltage" processor in a "low voltage" application avoided paying the traditional price premium for an officially certified low voltage version. However again like overclocking there is no guarantee of success, and the builder's time researching given system/processor combinations and especially the time and tedium of performing many iterations of stability testing need to be considered. The usefulness of underclocking (again like overclocking) is determined by what processor offerings, prices, and availability are at the specific time of the build. Underclocking is also sometimes used when
troubleshooting
Troubleshooting is a form of problem solving, often applied to repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it, and make the product or process op ...
.
Enthusiast culture
Overclocking has become more accessible with motherboard makers offering overclocking as a marketing feature on their mainstream product lines. However, the practice is embraced more by
enthusiasts
In modern usage, enthusiasm refers to intense enjoyment, interest, or approval expressed by a person. The term is related to playfulness, inventiveness, optimism and high energy. The word was originally used to refer to a person possessed by G ...
than professional users, as overclocking carries a risk of reduced reliability, accuracy and damage to data and equipment. Additionally, most manufacturer warranties and service agreements do not cover overclocked components nor any incidental damages caused by their use. While overclocking can still be an option for increasing personal computing capacity, and thus workflow productivity for professional users, the importance of stability testing components thoroughly ''before'' employing them into a production environment cannot be overstated.
Overclocking offers several draws for overclocking enthusiasts. Overclocking allows testing of components at speeds not currently offered by the manufacturer, or at speeds only officially offered on specialized, higher-priced versions of the product. A general trend in the computing industry is that new technologies tend to debut in the high-end market first, then later trickle down to the performance and mainstream market. If the high-end part only differs by an increased clock speed, an enthusiast can attempt to overclock a mainstream part to simulate the high-end offering. This can give insight on how over-the-horizon technologies will perform before they are officially available on the mainstream market, which can be especially helpful for other users considering if they should plan ahead to purchase or upgrade to the new feature when it is officially released.
Some hobbyists enjoy building, tuning, and "Hot-Rodding" their systems in competitive benchmarking competitions, competing with other like-minded users for high scores in standardized computer benchmark suites. Others will purchase a low-cost model of a component in a given product line, and attempt to overclock that part to match a more expensive model's stock performance. Another approach is overclocking older components to attempt to keep pace with increasing
system requirements and extend the useful service life of the older part or at least delay a purchase of new hardware solely for performance reasons. Another rationale for overclocking older equipment is even if overclocking stresses equipment to the point of failure earlier, little is lost as it is already
depreciated
In accountancy, depreciation is a term that refers to two aspects of the same concept: first, the actual decrease of fair value of an asset, such as the decrease in value of factory equipment each year as it is used and wear, and second, the a ...
, and would have needed to be replaced in any case.
Components
Technically any component that uses a timer (or clock) to synchronize its internal operations can be overclocked. Most efforts for computer components however focus on specific components, such as,
processors
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, ...
(a.k.a. CPU),
video card
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer mo ...
s,
motherboard chipset
In a computer system, a chipset is a set of electronic components in one or more integrated circuits known as a "Data Flow Management System" that manages the data flow between the processor, memory and peripherals. It is usually found on the mo ...
s, and
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
. Most modern processors derive their effective operating speeds by multiplying a base clock (processor bus speed) by an internal multiplier within the processor (the
CPU multiplier
In computing, the clock multiplier (or CPU multiplier or bus/core ratio) sets the ratio of an internal CPU clock rate to the externally supplied clock. A CPU with a 10x multiplier will thus see 10 internal cycles (produced by PLL-based frequency ...
) to attain their final speed.
Computer processors generally are overclocked by manipulating the
CPU multiplier
In computing, the clock multiplier (or CPU multiplier or bus/core ratio) sets the ratio of an internal CPU clock rate to the externally supplied clock. A CPU with a 10x multiplier will thus see 10 internal cycles (produced by PLL-based frequency ...
if that option is available, but the processor and other components can also be overclocked by increasing the base speed of the
bus clock. Some systems allow additional tuning of other clocks (such as a
system clock) that influence the bus clock speed that, again is multiplied by the processor to allow for finer adjustments of the final processor speed.
Most
OEM systems
An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...
do not expose to the user the adjustments needed to change processor clock speed or voltage in the BIOS of the OEM's motherboard, which precludes overclocking (for warranty and support reasons). The same processor installed on a different motherboard offering adjustments will allow the user to change them.
Any given component will ultimately stop operating reliably past a certain clock speed. Components will generally show some sort of malfunctioning behavior or other indication of compromised stability that alerts the user that a given speed is not stable, but there is always a possibility that a component will permanently fail without warning, even if voltages are kept within some pre-determined safe values. The maximum speed is determined by overclocking to the point of first instability, then accepting the last stable slower setting. Components are only guaranteed to operate correctly up to their rated values; beyond that different samples may have different overclocking potential. The end-point of a given overclock is determined by parameters such as available CPU multipliers, bus dividers,
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
s; the user's ability to manage thermal loads, cooling techniques; and several other factors of the individual devices themselves such as semiconductor clock and thermal tolerances, interaction with other components and the rest of the system.
Considerations
There are several things to be considered when overclocking. First is to ensure that the component is supplied with adequate power at a voltage sufficient to operate at the new
clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
. Supplying the power with improper settings or applying excessive
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
can permanently damage a component.
In a professional production environment, overclocking is only likely to be used where the increase in speed justifies the cost of the expert support required, the possibly reduced reliability, the consequent effect on maintenance contracts and warranties, and the higher power consumption. If faster speed is required it is often cheaper when all costs are considered to buy faster hardware.
Cooling
All
electronic circuits
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electrical ...
produce heat generated by the movement of electric current. As clock frequencies in
digital circuits and voltage applied increase, the heat generated by components running at the higher performance levels also increases. The relationship between clock frequencies and
thermal design power
The thermal design power (TDP), sometimes called thermal design point, is the maximum amount of heat generated by a computer chip or component (often a CPU, GPU or system on a chip) that the cooling system in a computer is designed to dissipate ...
(TDP) are linear. However, there is a limit to the maximum frequency which is called a "wall". To overcome this issue, overclockers raise the chip voltage to increase the overclocking potential. Voltage increases power consumption and consequently heat generation significantly (proportionally to the square of the voltage in a linear circuit, for example); this requires more cooling to avoid damaging the hardware by overheating. In addition, some digital circuits slow down at high temperatures due to changes in
MOSFET device characteristics. Conversely, the overclocker may decide to ''decrease'' the chip voltage while overclocking (a process known as undervolting), to reduce heat emissions while performance remains optimal.
Stock cooling systems are designed for the amount of power produced during non-overclocked use; overclocked circuits can require more cooling, such as by powerful
fans
Fan commonly refers to:
* Fan (machine), a machine for producing airflow, often used for cooling
** Hand fan, an implement held and waved by hand to move air for cooling
* Fan (person), short for fanatic; an enthusiast or supporter, especially wit ...
, larger
heat sink
A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, th ...
s,
heat pipe
A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces.
At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor b ...
s and
water cooling
Cooling tower and water discharge of a nuclear power plant
Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non ...
. Mass, shape, and material all influence the ability of a heatsink to dissipate heat. Efficient heatsinks are often made entirely of
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
, which has high
thermal conductivity
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...
, but is expensive.
Aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
is more widely used; it has good thermal characteristics, though not as good as copper, and is significantly cheaper. Cheaper materials such as steel do not have good thermal characteristics.
Heat pipe
A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces.
At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor b ...
s can be used to improve conductivity. Many heatsinks combine two or more materials to achieve a balance between performance and cost.
[
]
Water cooling carries waste heat
Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
to a radiator. Thermoelectric cooling
Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side o ...
devices which actually refrigerate using the Peltier effect
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when ...
can help with high thermal design power
The thermal design power (TDP), sometimes called thermal design point, is the maximum amount of heat generated by a computer chip or component (often a CPU, GPU or system on a chip) that the cooling system in a computer is designed to dissipate ...
(TDP) processors made by Intel and AMD in the early twenty-first century. Thermoelectric cooling devices create temperature differences between two plates by running an electric current through the plates. This method of cooling is highly effective, but itself generates significant heat elsewhere which must be carried away, often by a convection-based heatsink or a water cooling
Cooling tower and water discharge of a nuclear power plant
Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non ...
system.
Other cooling methods are forced convection
Forced convection is a mechanism, or type of transport, in which fluid motion is generated by an external source (like a pump, fan, suction device, etc.). Alongside natural convection, thermal radiation, and thermal conduction it is one of the m ...
and phase transition
In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states o ...
cooling which is used in refrigerators and can be adapted for computer use. Liquid nitrogen, liquid helium
Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity.
At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temp ...
, and dry ice
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily ...
are used as coolants in extreme cases, such as record-setting attempts or one-off experiments rather than cooling an everyday system. In June 2006, IBM and Georgia Institute of Technology jointly announced a new record in silicon-based chip clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
(the rate a transistor can be switched at, not the CPU clock rate) above 500 GHz, which was done by cooling the chip to using liquid helium. Set in November 2012, the CPU Frequency World Record is 8.794 GHz as of January 2022. These extreme methods are generally impractical in the long term, as they require refilling reservoirs of vaporizing coolant, and condensation can form on chilled components.[ Moreover, ]silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...
-based junction gate field-effect transistor
The junction-gate field-effect transistor (JFET) is one of the simplest types of field-effect transistor. JFETs are three-terminal semiconductor devices that can be used as electronically controlled switches or resistors, or to build amplifier ...
s (JFET) will degrade below temperatures of roughly and eventually cease to function or "freeze out" at since the silicon ceases to be semiconducting, so using extremely cold coolants may cause devices to fail.
Submersion cooling, used by the Cray-2
The Cray-2 is a supercomputer with four vector processors made by Cray Research starting in 1985. At 1.9 GFLOPS peak performance, it was the fastest machine in the world when it was released, replacing the Cray X-MP in that spot. It was, i ...
supercomputer, involves sinking a part of computer system directly into a chilled liquid that is thermally conductive but has low electrical conductivity. The advantage of this technique is that no condensation can form on components.[ A good submersion liquid is ]Fluorinert
Fluorinert is the trademarked brand name for the line of electronics coolant liquids sold commercially by 3M. As perfluorinated compounds (PFCs), all Fluorinert variants have an extremely high Global Warming Potential (GWP), so should be used wit ...
made by 3M, which is expensive. Another option is mineral oil
Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils.
The name 'mineral oil' by itself is imprecise, ...
, but impurities such as those in water might cause it to conduct electricity.
Amateur overclocking enthusiasts have used a mixture of dry ice
Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily ...
and a solvent with a low freezing point, such as acetone
Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour.
Acetone is miscib ...
or isopropyl alcohol
Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group ( chemical formula ) it is the s ...
. This cooling bath, often used in laboratories, achieves a temperature of −78 °C. However, this practice is discouraged due to its safety risks; the solvents are flammable and volatile, and dry ice can cause frostbite
Frostbite is a skin injury that occurs when exposed to extreme low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occurs in the ha ...
(through contact with exposed skin) and suffocation (due to the large volume of carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
generated when it sublimes).
Stability and functional correctness
As an overclocked component operates outside of the manufacturer's recommended operating conditions, it may function incorrectly, leading to system instability. Another risk is silent data corruption
Silent may mean any of the following:
People with the name
* Silent George, George Stone (outfielder) (1876–1945), American Major League Baseball outfielder and batting champion
* Brandon Silent (born 1973), South African former footballer
* C ...
by undetected errors. Such failures might never be correctly diagnosed and may instead be incorrectly attributed to software bugs in applications, device drivers
In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and ot ...
, or the operating system. Overclocked use may permanently damage components enough to cause them to misbehave (even under normal operating conditions) without becoming totally unusable.
A large-scale 2011 field study of hardware faults causing a system crash for consumer PCs and laptops showed a four to 20 times increase (depending on CPU manufacturer) in system crashes due to CPU failure for overclocked computers over an eight-month period.
In general, overclockers claim that testing can ensure that an overclocked system is stable and functioning correctly. Although software tools are available for testing hardware stability, it is generally impossible for any private individual to thoroughly test the functionality of a processor. Achieving good fault coverage {{Unreferenced, date=November 2022
Fault coverage refers to the percentage of some type of fault that can be detected during the test of any engineered system. High fault coverage is particularly valuable during manufacturing test, and techniques ...
requires immense engineering effort; even with all of the resources dedicated to validation by manufacturers, faulty components and even design faults are not always detected.
A particular "stress test" can verify only the functionality of the specific instruction sequence used in combination with the data and may not detect faults in those operations. For example, an arithmetic operation may produce the correct result but incorrect flags
A flag is a piece of textile, fabric (most often rectangular or quadrilateral) with a distinctive design and colours. It is used as a symbol, a signalling device, or for decoration. The term ''flag'' is also used to refer to the graphic desi ...
; if the flags are not checked, the error will go undetected.
To further complicate matters, in process technologies such as silicon on insulator (SOI), devices display hysteresis—a circuit's performance is affected by the events of the past, so without carefully targeted tests it is possible for a particular sequence of state changes to work at overclocked rates in one situation but not another even if the voltage and temperature are the same. Often, an overclocked system which passes stress tests experiences instabilities in other programs.
In overclocking circles, "stress tests" or "torture tests" are used to check for correct operation of a component. These workloads are selected as they put a very high load on the component of interest (e.g. a graphically intensive application for testing video cards, or different math-intensive applications for testing general CPUs). Popular stress tests include Prime95
Prime95, also distributed as the command-line utility mprime for FreeBSD and Linux, is a freeware application written by George Woltman. It is the official client of the Great Internet Mersenne Prime Search (GIMPS), a volunteer computing projec ...
, Everest
Mount Everest (; Tibetic languages, Tibetan: ''Chomolungma'' ; ) is List of highest mountains on Earth, Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border ru ...
, Superpi, OCCT, AIDA64, Linpack (via the LinX and IntelBurnTest GUI
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
s), SiSoftware Sandra, BOINC
The Berkeley Open Infrastructure for Network Computing (BOINC, pronounced – rhymes with "oink") is an open-source middleware system for volunteer computing (a type of distributed computing). Developed originally to support SETI@home, it beca ...
, Intel Thermal Analysis Tool and Memtest86
MemTest86 and Memtest86+ are memory test software programs designed to test and stress test an x86 architecture computer's random-access memory (RAM) for errors, by writing test patterns to most memory addresses, reading back the data, and comp ...
. The hope is that any functional-correctness issues with the overclocked component will manifest themselves during these tests, and if no errors are detected during the test, then the component is deemed "stable". Since fault coverage is important in stability testing, the tests are often run for long periods of time, hours or even days. An overclocked computer is sometimes described using the number of hours and the stability program used, such as "prime 12 hours stable".
Factors allowing overclocking
Overclockability arises in part due to the economics of the manufacturing processes of CPUs and other components. In many cases components are manufactured by the same process, and tested after manufacture to determine their actual maximum ratings. Components are then marked with a rating chosen by the market needs of the semiconductor manufacturer. If manufacturing yield is high, more higher-rated components than required may be produced, and the manufacturer may mark and sell higher-performing components as lower-rated for marketing reasons. In some cases, the true maximum rating of the component may exceed even the highest rated component sold. Many devices sold with a lower rating may behave in all ways as higher-rated ones, while in the worst case operation at the higher rating may be more problematical.
Notably, higher clocks must always mean greater waste heat generation, as semiconductors set to high must dump to ground more often. In some cases, this means that the chief drawback of the overclocked part is far more heat dissipated than the maximums published by the manufacturer. Pentium architect Bob Colwell
Robert P. "Bob" Colwell (born 1954) is an electrical engineer who worked at Intel and later served as Director of the Microsystems Technology Office (MTO) at DARPA. He was the chief IA-32 architect on the Pentium Pro, Pentium II, Pentium III, and P ...
calls overclocking an "uncontrolled experiment in better-than-worst-case system operation".
Measuring effects of overclocking
Benchmarks are used to evaluate performance, and they can become a kind of "sport" in which users compete for the highest scores. As discussed above, stability and functional correctness may be compromised when overclocking, and meaningful benchmark results depend on the correct execution of the benchmark. Because of this, benchmark scores may be qualified with stability and correctness notes (e.g. an overclocker may report a score, noting that the benchmark only runs to completion 1 in 5 times, or that signs of incorrect execution such as display corruption are visible while running the benchmark). A widely used test of stability is Prime95, which has built-in error checking that fails if the computer is unstable.
Using only the benchmark scores, it may be difficult to judge the difference overclocking makes to the overall performance of a computer. For example, some benchmarks test only one aspect of the system, such as memory bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
, without taking into consideration how higher clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
s in this aspect will improve the system performance as a whole. Apart from demanding applications such as video encoding, high-demand database
In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases s ...
s and scientific computing
Computational science, also known as scientific computing or scientific computation (SC), is a field in mathematics that uses advanced computing capabilities to understand and solve complex problems. It is an area of science that spans many disc ...
, memory bandwidth
Memory bandwidth is the rate at which data can be read from or stored into a semiconductor memory by a processor. Memory bandwidth is usually expressed in units of bytes/second, though this can vary for systems with natural data sizes that are n ...
is typically not a bottleneck
Bottleneck literally refers to the narrowed portion (neck) of a bottle near its opening, which limit the rate of outflow, and may describe any object of a similar shape. The literal neck of a bottle was originally used to play what is now known as ...
, so a great increase in memory bandwidth may be unnoticeable to a user depending on the applications used. Other benchmarks, such as 3DMark
3DMark is a computer benchmarking tool created and developed by UL, (formerly Futuremark), to determine the performance of a computer's 3D graphic rendering and CPU workload processing capabilities. Running 3DMark produces a 3DMark score, with h ...
, attempt to replicate game conditions.
Manufacturer and vendor overclocking
Commercial system builders or component resellers sometimes overclock to sell items at higher profit margins. The seller makes more money by overclocking lower-priced components which are found to operate correctly and selling equipment at prices appropriate for higher-rated components. While the equipment will normally operate correctly, this practice may be considered fraudulent if the buyer is unaware of it.
Overclocking is sometimes offered as a legitimate service or feature for consumers, in which a manufacturer or retailer tests the overclocking capability of processors, memory, video cards, and other hardware products. Several video card manufactures now offer factory-overclocked versions of their graphics accelerators, complete with a warranty, usually at a price intermediate between that of the standard product and a non-overclocked product of higher performance.
It is speculated that manufacturers implement overclocking prevention mechanisms such as CPU multiplier locking to prevent users from buying lower-priced items and overclocking them. These measures are sometimes marketed as a consumer protection benefit, but are often criticized by buyers.
Many motherboards are sold, and advertised, with extensive facilities for overclocking implemented in hardware and controlled by BIOS settings.
CPU multiplier locking
CPU multiplier locking is the process of permanently setting a CPU's clock multiplier. AMD
Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
CPUs are unlocked in early editions of a model and locked in later editions, but nearly all Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
CPUs are locked and recent models are very resistant to unlocking to prevent overclocking by users. AMD ships unlocked CPUs with their Opteron
Opteron is AMD's x86 former server and workstation processor line, and was the first processor which supported the AMD64 instruction set architecture (known generically as x86-64 or AMD64). It was released on April 22, 2003, with the ''Sledg ...
, FX, Ryzen
Ryzen ( ) is a brand of multi-core x86-64 microprocessors designed and marketed by AMD for desktop, mobile, server, and embedded platforms based on the Zen microarchitecture. It consists of central processing units (CPUs) marketed for mainst ...
and Black Series line-up, while Intel uses the monikers of "Extreme Edition" and "K-Series." Intel usually has one or two Extreme Edition CPUs on the market as well as X series and K series CPUs analogous to AMD's Black Edition. AMD has the majority of their desktop range in a Black Edition.
Users usually unlock CPUs to allow overclocking, but sometimes to allow for underclocking
Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified. Underclocking is used to reduce a computer's power consumption, increase battery life, red ...
in order to maintain the front side bus
A front-side bus (FSB) is a computer communication interface ( bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the ...
speed (on older CPUs) compatibility with certain motherboards. Unlocking generally invalidates the manufacturer's warranty, and mistakes can cripple or destroy a CPU. Locking a chip's clock multiplier does not necessarily prevent users from overclocking, as the speed of the front-side bus or PCI multiplier (on newer CPUs) may still be changed to provide a performance increase. AMD Athlon
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon (now called Athlon Classic) was the first seventh-generation x86 processor and the fi ...
and Athlon XP
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon (now called Athlon Classic) was the first seventh-generation x86 processor and the fi ...
CPUs are generally unlocked by connecting bridges ( jumper-like points) on the top of the CPU with conductive
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gene ...
paint or pencil lead
A graphite pencil, also called a lead pencil, is a type of pencil in which a thin graphite core is embedded in a shell of other material. The pencil shell is typically wooden, but can be made of plastic or recycled paper.
History
A large deposi ...
. Other CPU models may require different procedures.
Increasing front-side bus or northbridge/PCI clocks can overclock locked CPUs, but this throws many system frequencies out of sync, since the RAM and PCI frequencies are modified as well.
One of the easiest ways to unlock older AMD Athlon XP CPUs was called the ''pin mod'' method, because it was possible to unlock the CPU without permanently modifying bridges. A user could simply put one wire (or some more for a new multiplier/Vcore) into the socket to unlock the CPU. More recently however, notably with Intel's Skylake architecture, Intel had a bug with the Skylake (6th gen Core) processors where the base clock could be increased past 102.7 MHz, however functionality of certain features would not work. Intel intended to block base clock (BCLK) overclocking of locked processors when designing the Skylake architecture to prevent consumers from purchasing cheaper components and overclocking to previously-unseen heights (since the CPU's BCLK was no longer tied to the PCI buses), however for LGA1151, the 6th generation "Skylake" processors were able to be overclocked past 102.7 MHz (which was the intended limit by Intel, and was later mandated through later BIOS updates). All other unlocked processors from LGA1151 and v2 (including 7th, 8th, and 9th generation) and BGA1440 allow for BCLK overclocking (as long as the OEM allows it), while all other locked processors from 7th, 8th, and 9th gen were not able to go past 102.7 Mhz. 10th gen however, could reach 103 Mhz on the BCLK.
Advantages
* Higher performance in games, en-/decoding, video editing and system tasks at no additional direct monetary expense, but with increased electrical consumption and thermal output.
* System optimization: Some systems have " bottlenecks", where small overclocking of one component can help realize the full potential of another component to a greater percentage than when just the limiting hardware itself is overclocked. For instance: many motherboards with AMD Athlon 64 processors limit the clock rate of four units of RAM to 333 MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
. However, the memory performance is computed by dividing the processor clock rate (which is a base number times a CPU multiplier
In computing, the clock multiplier (or CPU multiplier or bus/core ratio) sets the ratio of an internal CPU clock rate to the externally supplied clock. A CPU with a 10x multiplier will thus see 10 internal cycles (produced by PLL-based frequency ...
, for instance 1.8 GHz is most likely 9×200 MHz) by a fixed integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign ( −1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the languag ...
such that, at a stock clock rate, the RAM would run at a clock rate near 333 MHz. Manipulating elements of how the processor clock rate is set (usually adjusting the multiplier), it is often possible to overclock the processor a small amount, around 5-10%, and gain a small increase in RAM clock rate and/or reduction in RAM latency timings.
* It can be cheaper to purchase a lower performance component and overclock it to the clock rate of a more expensive component.
* Extending life on older equipment (through underclocking/undervolting).
Disadvantages
General
* Higher clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
s and voltages increase power consumption, also increasing electricity cost and heat production. The additional heat increases the ambient air temperature within the system case, which may affect other components. The hot air blown out of the case heats the room it's in.
* Fan noise: High-performance fans running at maximum speed used for the required degree of cooling of an overclocked machine can be noisy, some producing 50 dB or more of noise. When maximum cooling is not required, in any equipment, fan speeds can be reduced below the maximum: fan noise has been found to be roughly proportional to the fifth power of fan speed; halving speed reduces noise by about 15 dB. Fan noise can be reduced by design improvements, e.g. with aerodynamically optimized blades for smoother airflow, reducing noise to around 20 dB at approximately 1 metre or larger fans rotating more slowly, which produce less noise than smaller, faster fans with the same airflow. Acoustical insulation inside the case e.g. acoustic foam can reduce noise. Additional cooling methods which do not use fans can be used, such as liquid and phase-change cooling.
* An overclocked computer may become unreliable. For example: Microsoft Windows may appear to work with no problems, but when it is re-installed or upgraded, error messages may be received such as a "file copy error" during Windows Setup. Because installing Windows is very memory-intensive, decoding errors may occur when files are extracted from the Windows XP CD-ROM
* The lifespan of semiconductor components may be reduced by increased voltages and heat.
* Warranties may be voided by overclocking.
Risks of overclocking
* Increasing the operation frequency of a component will usually increase its thermal output in a linear fashion, while an increase in voltage usually causes thermal power to increase quadratically. Excessive voltages or improper cooling may cause chip temperatures to rise to dangerous levels, causing the chip to be damaged or destroyed.
* Exotic cooling methods used to facilitate overclocking such as water cooling are more likely to cause damage if they malfunction. Sub-ambient cooling methods such as phase-change cooling or liquid nitrogen will cause water condensation, which will cause electrical damage unless controlled; some methods include using kneaded erasers or shop towels to catch the condensation.
Limitations
Overclocking components can only be of noticeable benefit if the component is on the critical path for a process, if it is a bottleneck. If disk access or the speed of an Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
connection limit the speed of a process, a 20% increase in processor speed is unlikely to be noticed, however there are some scenarios where increasing the clock speed of a processor actually allows an SSD to be read and written to faster. Overclocking a CPU will not noticeably benefit a game when a graphics card's performance is the "bottleneck" of the game.
Graphics cards
Graphics cards can also be overclocked. There are utilities
A public utility company (usually just utility) is an organization that maintains the infrastructure for a public service (often also providing a service using that infrastructure). Public utilities are subject to forms of public control and ...
to achieve this, such as EVGA's Precision, RivaTuner, AMD
Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
Overdrive (on AMD
Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
cards only), MSI Afterburner, Zotac Firestorm, and the PEG Link Mode on Asus motherboards. Overclocking a GPU will often yield a marked increase in performance in synthetic benchmarks, usually reflected in game performance.Alt+Esc , GTX 780 Overclocking Guide
/ref> It is sometimes possible to see that a graphics card is being pushed beyond its limits before any permanent damage is done by observing on-screen artifacts or unexpected system crashes. It is common to run into one of those problems when overclocking graphics cards; both symptoms at the same time usually means that the card is severely pushed beyond its heat, clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
, and/or voltage limits, however if seen when not overclocked, they indicate a faulty card. After a reboot, video settings are reset to standard values stored in the graphics card firmware, and the maximum clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
of that specific card is now deducted.
Some overclockers apply a potentiometer
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
The measuring instrum ...
to the graphics card to manually adjust the voltage (which usually invalidates the warranty). This allows for finer adjustments, as overclocking software for graphics cards can only go so far. Excessive voltage increases may damage or destroy components on the graphics card or the entire graphics card itself (practically speaking).
RAM
Alternatives
Flashing and unlocking can be used to improve the performance of a video card
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer mo ...
, without technically overclocking (but is much riskier than overclocking just through software).
''Flashing'' refers to using the firmware of a different card with the same (or sometimes similar) core and compatible firmware, effectively making it a higher model card; it can be difficult, and may be irreversible. Sometimes standalone software to modify the firmware files can be found, e.g. NiBiTor (GeForce 6/7 series are well regarded in this aspect), without using firmware for a better model video card. For example, video cards with 3D accelerators (most, ) have two voltage and clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
settings, one for 2D and one for 3D, but were designed to operate with ''three'' voltage stages, the third being somewhere between the aforementioned two, serving as a fallback when the card overheats or as a middle-stage when going from 2D to 3D operation mode. Therefore, it could be wise to set this middle-stage prior to "serious" overclocking, specifically because of this fallback ability; the card can drop down to this clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
, reducing by a few (or sometimes a few dozen, depending on the setting) percent of its efficiency and cool down, without dropping out of 3D mode (and afterwards return to the desired high performance clock and voltage settings).
Some cards have abilities not directly connected with overclocking. For example, Nvidia's GeForce 6600GT (AGP flavor) has a temperature monitor used internally by the card, invisible to the user if standard firmware is used. Modifying the firmware can display a 'Temperature' tab.
''Unlocking'' refers to enabling extra pipelines or pixel shader
In computer graphics, a shader is a computer program that calculates the appropriate levels of light, darkness, and color during the Rendering (computer graphics), rendering of a 3D scene - a process known as ''shading''. Shaders have evolved ...
s. The 6800LE, the 6800GS and 6800 ( AGP models only) were some of the first cards to benefit from unlocking. While these models have either 8 or 12 pipes enabled, they share the same 16x6 GPU
A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...
core as a 6800GT or Ultra, but pipelines and shaders beyond those specified are disabled; the GPU may be fully functional, or may have been found to have faults which do not affect operation at the lower specification. GPUs found to be fully functional can be unlocked successfully, although it is not possible to be sure that there are undiscovered faults; in the worst case the card may become permanently unusable.
History
Overclocked processors first became commercially available in 1983, when AMD sold an overclocked version of the Intel 8088
The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and ...
CPU. In 1984, some consumers were overclocking IBM's version of the Intel 80286
The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non- multiplexed address and data buses and also the ...
CPU by replacing the clock crystal. Xeon W-3175X is the only Xeon with a multiplier unlocked for overclocking.
See also
* Clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
* CPU-Z
CPU-Z is a freeware system profiling and monitoring application for Microsoft Windows and Android that detects the central processing unit, RAM, motherboard chip-set, and other hardware features of a modern personal computer or Android device. ...
* Double boot
* Dynamic voltage scaling
Dynamic voltage scaling is a power management technique in computer architecture, where the voltage used in a component is increased or decreased, depending upon circumstances. Dynamic voltage scaling to increase voltage is known as overvolting; d ...
* POWER8 on-chip controller (OCC)
* Serial presence detect (SPD)
* Super PI
* Underclocking
Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified. Underclocking is used to reduce a computer's power consumption, increase battery life, red ...
* UNIVAC I Overdrive, 1952 unofficial modification
References
;Notes
*
External links
OverClocked inside
How to Overclock a PC
WikiHow
Overclocking and benchmark databases
OC Database of all PC hardware for the past decade
(applications, modifications and more)
HWBOT: Worldwide Overclocking League – Overclocking competition and data
Comprehensive CPU OC Database
Segunda Convencion Nacional de OC: Overclocking Extremo
by Imperio Gamer
{{Computer processor power management technologies
Computer hardware tuning
Clock signal
Hobbies
IBM PC compatibles