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A motherboard (also called mainboard, main circuit board, or mobo) is the main
printed circuit board A printed circuit board (PCB) is a laminated sandwich structure of conductive and insulating layers. PCBs have two complementary functions. The first is to affix electronic components An electronic component is any basic discrete device or ...

printed circuit board
(PCB) in general-purpose computers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the
central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of individual electroni ...

central processing unit
(CPU) and
memory Memory is the faculty of the by which or is , stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If s could not be remembered, it would be impossible for language, r ...
, and provides connectors for other
peripherals A peripheral or peripheral device is an auxiliary device used to put information into and get information out of the computer. The term peripheral device refers to all hardware components that are attached to a computer and are controlled by the co ...
. Unlike a
backplane A backplane (or "backplane system") is a group of electrical connector An electrical connector is an electromechanical device used to join electrical conductors and create an electrical circuit An electrical network is an interconnec ...

backplane
, a motherboard usually contains significant sub-systems, such as the central processor, the chipset's
input/output In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest commo ...
and memory controllers,
interface Interface or interfacing may refer to: Academic journals * Interface (journal), ''Interface'' (journal), by the Electrochemical Society * ''Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Lin ...
connectors, and other components integrated for general use. ''Motherboard'' means specifically a PCB with expansion capabilities. As the name suggests, this board is often referred to as the "mother" of all components attached to it, which often include peripherals, interface cards, and
daughterboard Modern EEPROM chip suitable for storing expansion card configuration electronically In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentati ...
s:
sound card A sound card (also known as an audio card) is an internal expansion card Modern EEPROM chip suitable for storing expansion card configuration electronically In computing Computing is any goal-oriented activity requiring, benefiting f ...

sound card
s,
video card A graphics card (also called a video card, display card, graphics adapter, video adapter, or display adapter) is an expansion card which generates a feed of output images to a display device (such as a computer monitor). Frequently, these are ad ...

video card
s,
network card A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) is a computer hardware Computer hardware includes the physical parts of a compute ...

network card
s,
host bus adapter In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern compute ...
s,
TV tuner card A TV tuner card is a kind of television tuner that allows television Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, ...
s,
IEEE 1394 IEEE 1394 is an interface standard for a serial communication, serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple Inc., Apple in cooperation with a number ...
cards; and a variety of other custom components. Similarly, the term ''mainboard'' describes a device with a single board and no additional expansions or capability, such as controlling boards in laser printers, television sets, washing machines, mobile phones, and other
embedded system An embedded system is a computer system A computer is a machine that can be programmed to carry out Sequence, sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Co ...
s with limited expansion abilities.


History

Prior to the invention of the
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip ...

microprocessor
, the digital computer consisted of multiple printed circuit boards in a card-cage case with components connected by a
backplane A backplane (or "backplane system") is a group of electrical connector An electrical connector is an electromechanical device used to join electrical conductors and create an electrical circuit An electrical network is an interconnec ...

backplane
, a set of interconnected sockets. In very old designs, copper wires were the discrete connections between card connector pins, but printed circuit boards soon became the standard practice. The
central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of individual electroni ...

central processing unit
(CPU), memory, and
peripherals A peripheral or peripheral device is an auxiliary device used to put information into and get information out of the computer. The term peripheral device refers to all hardware components that are attached to a computer and are controlled by the co ...
were housed on individually printed circuit boards, which were plugged into the backplane. The ubiquitous
S-100 bus The S-100 bus or Altair bus, IEEE 696-1983 ''(withdrawn)'', is an early computer bus In computer architecture In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and ...
of the 1970s is an example of this type of backplane system. The most popular computers of the 1980s such as the
Apple II The Apple II (stylized as apple ][) is an and one of the world's first highly successful mass-produced products. It was designed primarily by ; oversaw the development of Apple II's foam-molded plastic case and developed the . It was in ...

Apple II
and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse-engineering and third-party replacement motherboards. Usually intended for building new computers compatible with the exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment. During the late 1980s and early 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard. In the late 1980s, personal computer motherboards began to include single ICs (also called
Super I/O Super I/O is a class of I/O controller integrated circuits that began to be used on personal computer motherboards in the late 1980s, originally as add-in cards, later embedded on the motherboards. A super I/O chip combines interfaces for a varie ...
chips) capable of supporting a set of low-speed peripherals:
PS/2 The Personal System/2 or PS/2 is IBM International Business Machines Corporation (IBM) is an American multinational technology company headquartered in Armonk, New York, with operations in over 170 countries. The company began in 1911, ...
keyboard and
mouse A mouse, plural mice, is a small mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which ...
,
floppy disk drive A floppy disk or floppy diskette (sometimes casually referred to as a floppy or diskette) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
,
serial port 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 computer hardware , hardware and so ...

serial port
s, and
parallel port 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 computer hardware , hardware a ...
s. By the late 1990s, many personal computer motherboards included consumer-grade embedded audio, video, storage, and networking functions without the need for any
expansion cards Modern EEPROM chip suitable for storing expansion card configuration electronically In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentati ...
at all; higher-end systems for 3D gaming and
computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great dea ...

computer graphics
typically retained only the graphics card as a separate component. Business PCs, workstations, and servers were more likely to need expansion cards, either for more robust functions, or for higher speeds; those systems often had fewer embedded components. Laptop and notebook computers that were developed in the 1990s integrated the most common peripherals. This even included motherboards with no upgradeable components, a trend that would continue as smaller systems were introduced after the turn of the century (like the
tablet computer A tablet computer, commonly shortened to tablet, is a mobile device A mobile device (or handheld computer) is a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations auto ...
and the
netbook The marketing term netbook identified small and inexpensive laptop computer, laptops that were sold from 2007 to around 2013; these were generally low-performance. While the ''name'' has fallen out of use, machines matching their descripti ...

netbook
). Memory, processors, network controllers, power source, and storage would be integrated into some systems.


Design

A motherboard provides the electrical connections by which the other components of the system communicate. Unlike a backplane, it also contains the central processing unit and hosts other subsystems and devices. A typical
desktop computer A desktop computer is a personal computer File:Crystal Project computer.png, upright=0.9, An artist's depiction of a 2000s-era desktop-style personal computer, which includes a metal case with the computing components, a display monitor and ...
has its
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip ...

microprocessor
,
main memory Computer data storage is a technology consisting of computer components and Data storage device, recording media that are used to retain digital data (computing), data. It is a core function and fundamental component of computers. The cent ...
, and other essential components connected to the motherboard. Other components such as
external storage 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 computer hardware , hardware and softwa ...
, controllers for
video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active d ...

video
display and
sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the b ...

sound
, and peripheral devices may be attached to the motherboard as plug-in cards or via cables; in modern microcomputers, it is increasingly common to integrate some of these peripherals into the motherboard itself. An important component of a motherboard is the microprocessor's supporting
chipset In a computer system, a chipset is a set of electronic components An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components ar ...

chipset
, which provides the supporting interfaces between the CPU and the various
buses A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a designed to carry many s. Buses can have a capacity as high as 300 passengers. The most common type is the , with larger loads carried by and es, and sm ...
and external components. This chipset determines, to an extent, the features and capabilities of the motherboard. Modern motherboards include: *
CPU socket In computer hardware Computer hardware includes the physical parts of a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform ge ...
s (or CPU slots) in which one or more
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip ...

microprocessor
s may be installed. In the case of CPUs in
ball grid array A ball grid array (BGA) is a type of surface-mount File:SMDcompared.jpeg">A MOSFET transistor, placed upon a British postage stamp for size comparison. Surface-mount technology (SMT) is a method in which the electrical components are mount ...
packages, such as the
VIA Nano The VIA Nano (formerly Code name#Commercial code names in the computer industry, code-named VIA Isaiah) is a 64-bit CPU for personal computers. The VIA Nano was released by VIA Technologies in 2008 after five years of development by its CPU divi ...
and the
Goldmont Plus Goldmont Plus is a microarchitecture In computer engineering Computer engineering (CoE or CpE) is a branch of engineering Engineering is the use of scientific method, scientific principles to design and build machines, structure ...
, the CPU is directly soldered to the motherboard. * Memory slots into which the system's main memory is to be installed, typically in the form of
DIMM A DIMM () or dual in-line memory module, commonly called a RAM stick, comprises a series of dynamic random-access memory integrated circuits. These modules are mounted on a printed circuit board and designed for use in personal computers, workst ...
modules containing
DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access Random access (more precisely and more generally called direct access) is the ability to access an arbitrary element of a sequence in equal time or any datum fr ...
chips can be
DDR3 Double Data Rate 3 Synchronous Dynamic Random-Access Memory (DDR3 SDRAM) is a type of synchronous dynamic random-access memory Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any Dynamic RAM, DRAM where the opera ...
,
DDR4 Double Data Rate 4 Synchronous Dynamic Random-Access Memory (DDR4 SDRAM) is a type of synchronous dynamic random-access memory Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any Dynamic RAM, DRAM where the operat ...
or
DDR5 Double Data Rate 5 Synchronous Dynamic Random-Access Memory (DDR5 SDRAM) is a type of synchronous dynamic random-access memory. Compared to its predecessor DDR4 SDRAM, DDR5 is planned to reduce power consumption, while doubling Bandwidth (computi ...
* The
chipset In a computer system, a chipset is a set of electronic components An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components ar ...

chipset
which forms an interface between the
CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuit File:PExdcr01CJC.jpg, 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of ...

CPU
,
main memory Computer data storage is a technology consisting of computer components and Data storage device, recording media that are used to retain digital data (computing), data. It is a core function and fundamental component of computers. The cent ...
, and peripheral buses *
Non-volatile memory Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retain stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data. Examples of non-volatile ...
chips (usually
Flash ROM Flash memory is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses act ...
in modern motherboards) containing the system's
firmware 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 computer hardware , hardware and soft ...
or
BIOS In computing, BIOS (, ); an acronym for Basic Input/Output System and also known as the System BIOS, ROM BIOS or PC BIOS) is firmware used to perform Computer hardware, hardware initialization during the booting process (power-on startup), and t ...

BIOS
* The
clock generator 200px, A laptop PC clock generator, based on the Silego chip A clock generator is an electronic oscillator that produces a clock signal In electronics Electronics comprises the physics, engineering, technology and applications that deal with ...
which produces the system
clock signal In electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active devices to control electron flow by amplifier, amplificati ...

clock signal
to synchronize the various components * Slots for
expansion card Modern EEPROM chip suitable for storing expansion card configuration electronically In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentati ...
s (the interface to the system via the buses supported by the chipset) * Power connectors, which receive electrical power from the computer
power supply #REDIRECT Power supply#REDIRECT Power supply A power supply is an electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage, el ...

power supply
and distribute it to the CPU, chipset, main memory, and expansion cards. , some
graphics card A graphics card (also called a video card, display card, graphics adapter, video adapter, or display adapter) is an expansion card Modern EEPROM chip suitable for storing expansion card configuration electronically In computing Compu ...
s (e.g. GeForce 8 and
Radeon R600 The graphics processing unit (GPU) codenamed Radeon R600 is the foundation of the Radeon HD 2000 series and the FireGL 2007 series video cards developed by ATI Technologies. The HD 2000 cards competed with nVidia's GeForce 8 series. Architecture ...
) require more power than the motherboard can provide, and thus dedicated connectors have been introduced to attach them directly to the power supply * Connectors for hard disk drives, optical disc drives, or solid-state drives, typically
SATA Serial ATA (SATA, abbreviated from Serial AT Attachment) is a computer bus In computer architecture In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implemen ...

SATA
and
NVMe NVM Express (NVMe) or Non-Volatile Memory Host Controller Interface Specification (NVMHCIS) is an open, logical-device interface specification A specification often refers to a set of documented requirements to be satisfied by a material, design ...
now. Additionally, nearly all motherboards include logic and connectors to support commonly used input devices, such as
USB Universal Serial Bus (USB) is an industry standard ''Industry Standard'' is a 1982 album by Dixie Dregs, The Dregs. It is their only album featuring vocals (by Alex Ligertwood of Santana (band), Santana and Patrick Simmons of The Doobie Brot ...

USB
for
mouse devices
mouse devices
and
keyboards Keyboard may refer to: Text input * Keyboard, part of a typewriter A typewriter is a machine, mechanical or electromechanical machine for typing characters similar to those produced by a printer's movable type. Typically, a typewriter has an arr ...

keyboards
. Early
personal computer A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or technician ...
s such as the
Apple II The Apple II (stylized as apple ][) is an and one of the world's first highly successful mass-produced products. It was designed primarily by ; oversaw the development of Apple II's foam-molded plastic case and developed the . It was in ...

Apple II
or IBM PC included only this minimal peripheral support on the motherboard. Occasionally video interface hardware was also integrated into the motherboard; for example, on the Apple II and rarely on IBM-compatible computers such as the IBM PC Jr. Additional peripherals such as
disk controller The disk controller is the controller Controller may refer to: Occupations * Controller or financial controller, or in government accounting comptroller A comptroller is a management Management (or managing) is the administration of an o ...
s and
serial port 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 computer hardware , hardware and so ...

serial port
s were provided as expansion cards. Given the high
thermal design power #REDIRECT Thermal design power#REDIRECT 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) th ...
of high-speed computer CPUs and components, modern motherboards nearly always include
heat sink File:Laptop Heatsink.jpg, 330px, Typical heatsink-fan combination found on a consumer laptop. The heatpipes which contain a working fluid make direct contact with the CPU and GPU, conducting heat away from the component and transferring it to the f ...

heat sink
s and mounting points for
fan Fan commonly refers to: * Fan (machine), a machine for producing airflow, often for cooling ** Hand fan, an implement held and waved by hand to move air * Fan (person), short for fanatic; an enthusiast or supporter, especially with regard to enterta ...
s to dissipate excess heat.


Form factor

Motherboards are produced in a variety of sizes and shape called
computer form factor In computing, the form factor is the specification of a motherboard – the dimensions, power supply type, location of mounting holes, number of ports on the back panel, etc. Specifically, in the IBM PC compatible industry, standard form factors ...
, some of which are specific to individual computer manufacturers. However, the motherboards used in IBM-compatible systems are designed to fit various
case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Case, the metallic enclosure component in modern firearm cartridge (firearms), cartridges * Bookcase, a piece of furniture used to store books * Briefcase or ...
sizes. , most
desktop computer A desktop computer is a personal computer File:Crystal Project computer.png, upright=0.9, An artist's depiction of a 2000s-era desktop-style personal computer, which includes a metal case with the computing components, a display monitor and ...
motherboards use the
ATX ATX (Advanced Technology eXtended) is a motherboard and power supply configuration specification developed by in 1995 to improve on previous like the . It was the first major change in , , and design in many years, improving standardization ...

ATX
standard form factor — even those found in
Macintosh The Macintosh (mainly Mac since 1998) is a family of personal computer A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be op ...

Macintosh
and
Sun The Sun is the star A star is an astronomical object consisting of a luminous spheroid of plasma (physics), plasma held together by its own gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many othe ...
computers, which have not been built from commodity components. A case's motherboard and
power supply unit A power supply is an electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to pow ...
(PSU) form factor must all match, though some smaller form factor motherboards of the same family will fit larger cases. For example, an ATX case will usually accommodate a
microATX microATX (sometimes referred to as μATX, uATX or mATX) is a standard for motherboard A motherboard (also called mainboard, main circuit board, system board, baseboard, planar board, logic board, or mobo) is the main printed circuit board A ...
motherboard. Laptop computers generally use highly integrated, miniaturized, and customized motherboards. This is one of the reasons that laptop computers are difficult to upgrade and expensive to repair. Often the failure of one laptop component requires the replacement of the entire motherboard, which is usually more expensive than a desktop motherboard


CPU sockets

A
CPU socket In computer hardware Computer hardware includes the physical parts of a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform ge ...
(central processing unit) or slot is an electrical component that attaches to a Printed Circuit Board (PCB) and is designed to house a CPU (also called a microprocessor). It is a special type of integrated circuit socket designed for very high pin counts. A CPU socket provides many functions, including a physical structure to support the CPU, support for a heat sink, facilitating replacement (as well as reducing cost), and most importantly, forming an electrical interface both with the CPU and the PCB. CPU sockets on the motherboard can most often be found in most desktop and
server computer 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 computer hardware , hardware and softw ...
s (laptops typically use surface mount CPUs), particularly those based on the
Intel x86 x86 is a family of instruction set architecture In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for th ...
architecture. A CPU socket type and motherboard chipset must support the CPU series and speed.


Integrated peripherals

With the steadily declining costs and size of
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of indiv ...

integrated circuit
s, it is now possible to include support for many
peripherals A peripheral or peripheral device is an auxiliary device used to put information into and get information out of the computer. The term peripheral device refers to all hardware components that are attached to a computer and are controlled by the co ...
on the motherboard. By combining many functions on one
PCB
PCB
, the physical size and total cost of the system may be reduced; highly integrated motherboards are thus especially popular in small form factor and budget computers. *
Disk controller The disk controller is the controller Controller may refer to: Occupations * Controller or financial controller, or in government accounting comptroller A comptroller is a management Management (or managing) is the administration of an o ...
s for
SATA Serial ATA (SATA, abbreviated from Serial AT Attachment) is a computer bus In computer architecture In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implemen ...

SATA
drives, and historical PATA drives. * Historical
floppy-disk controller A floppy-disk controller (FDC) is a special-purpose chip and associated disk controller The disk controller is the controller circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive. It also pro ...
* Integrated graphics controller supporting 2D and 3D graphics, with
VGA Video Graphics Array (VGA) is a video display controller A video display controller or VDC (also regularly called display engine, display interface) is an integrated circuit An integrated circuit or monolithic integrated circuit (also ...
,
DVI Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working GroupThe Digital Display Working Group (DDWG) was a group whose purpose was to define and maintain the Digital Visual Interface standard. It was ...

DVI
,
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary hardware, proprietary audio/video Interface (computing), interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant s ...

HDMI
,
DisplayPort DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association VESA (), formally known as Video Electronics Standards Association, is an ...

DisplayPort
and TV output * integrated sound card supporting 8-channel (7.1) audio and
S/PDIF S/PDIF (Sony/Philips Digital Interface) is a type of digital audio Digital audio is a representation of sound recorded in, or converted into, Digital signal (signal processing), digital form. In digital audio, the sound wave of the audio ...
output *
Ethernet Ethernet () is a family of wired computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...

Ethernet
network controller A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) is a computer hardware component that connects a computer to a computer network. Ear ...

network controller
for connection to a
LAN A local area network (LAN) is a computer network A computer network is a set of s sharing resources located on or provided by . The computers use common s over to communicate with each other. These interconnections are made up of te ...

LAN
and to receive
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 ''internetworking, network of networks'' that consist ...

Internet
*
USB Universal Serial Bus (USB) is an industry standard ''Industry Standard'' is a 1982 album by Dixie Dregs, The Dregs. It is their only album featuring vocals (by Alex Ligertwood of Santana (band), Santana and Patrick Simmons of The Doobie Brot ...
controller *
Wireless network interface controller A wireless network interface controller (WNIC) is a network interface controller A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) ...
*
Bluetooth Bluetooth is a short-range wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which ...

Bluetooth
controller * Temperature, voltage, and fan-speed sensors that allow
software Software is a collection of instructions Instruction or instructions may refer to: Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * I ...

software
to monitor the health of computer components.


Peripheral card slots

A typical motherboard will have a different number of connections depending on its standard and form factor. A standard, modern ATX motherboard will typically have two or three
PCI-Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial communication, serial computer expansion bus standard, designed to replace the older Conventional PCI, PCI, PCI-X and Acc ...
x16 connection for a graphics card, one or two legacy PCI slots for various expansion cards, and one or two PCI-E x1 (which has superseded PCI). A standard
EATX ATX (Advanced Technology eXtended) is a motherboard and power supply configuration specification developed by Intel in 1995 to improve on previous de facto standard, ''de facto'' standards like the AT (form factor), AT design. It was the first ...
motherboard will have two to four PCI-E x16 connection for graphics cards, and a varying number of PCI and PCI-E x1 slots. It can sometimes also have a PCI-E x4 slot (will vary between brands and models). Some motherboards have two or more PCI-E x16 slots, to allow more than 2 monitors without special hardware, or use a special graphics technology called SLI (for
Nvidia Nvidia CorporationOfficially written as NVIDIA and stylized in its logo as nVIDIA with the lowercase "n" the same height as the uppercase "VIDIA"; formerly stylized as ''n''VIDIA with a large italicized lowercase "n" on products from the mid 19 ...
) and
Crossfire Depiction of crossfire A crossfire (also known as interlocking fire) is a military term for the siting of weapons (often automatic weapon An automatic firearm is a firearm that continuously Chamber (firearms), chambers and fires Cartridge (firea ...
(for AMD). These allow 2 to 4 graphics cards to be linked together, to allow better performance in intensive graphical computing tasks, such as gaming, video editing, etc. In newer motherboards, the M.2 slots are for SSD and/or
Wireless network interface controller A wireless network interface controller (WNIC) is a network interface controller A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface, and by similar terms) ...
.


Temperature and reliability

Motherboards are generally air cooling, air cooled with
heat sink File:Laptop Heatsink.jpg, 330px, Typical heatsink-fan combination found on a consumer laptop. The heatpipes which contain a working fluid make direct contact with the CPU and GPU, conducting heat away from the component and transferring it to the f ...

heat sink
s often mounted on larger chips in modern motherboards. Insufficient or improper cooling can cause damage to the internal components of the computer, or cause it to crash (computing), crash. Passive cooling, or a single fan mounted on the power supply unit (computer), power supply, was sufficient for many desktop computer CPU's until the late 1990s; since then, most have required CPU fans mounted on heat sinks, due to rising clock speeds and power consumption. Most motherboards have connectors for additional computer fans and integrated temperature sensors to detect motherboard and CPU temperatures and controllable fan connectors which the
BIOS In computing, BIOS (, ); an acronym for Basic Input/Output System and also known as the System BIOS, ROM BIOS or PC BIOS) is firmware used to perform Computer hardware, hardware initialization during the booting process (power-on startup), and t ...

BIOS
or operating system can use to regulate fan speed. Alternatively computers can use a water-cooling#Computer usage, water cooling system instead of many fans. Some small form factor computers and home theater PCs designed for quiet and energy-efficient operation boast fan-less designs. This typically requires the use of a low-power CPU, as well as a careful layout of the motherboard and other Electronic component, components to allow for heat sink placement. A 2003 study found that some spurious computer crashes and general reliability issues, ranging from screen image distortions to I/O read/write errors, can be attributed not to
software Software is a collection of instructions Instruction or instructions may refer to: Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * I ...

software
or peripheral personal computer hardware, hardware but to aging capacitors on PC motherboards. Ultimately this was shown to be the result of a faulty electrolyte formulation, an issue termed capacitor plague. Modern motherboards use electrolytic capacitors to filter the Direct current, DC power distributed around the board. These capacitors age at a temperature-dependent rate, as their water based electrolytes slowly evaporate. This can lead to loss of capacitance and subsequent motherboard malfunctions due to voltage instabilities. While most capacitors are rated for 2000 hours of operation at , their expected design life roughly doubles for every below this. At a lifetime of 3 to 4 years can be expected. However, many manufacturers deliver substandard capacitors, which significantly reduce life expectancy. Inadequate case cooling and elevated temperatures around the CPU socket exacerbate this problem. With top blowers, the motherboard components can be kept under , effectively doubling the motherboard lifetime. Mid-range and high-end motherboards, on the other hand, use solid capacitors exclusively. For every 10 °C less, their average lifespan is multiplied approximately by three, resulting in a 6-times higher lifetime expectancy at . These capacitors may be rated for 5000, 10000 or 12000 hours of operation at , extending the projected lifetime in comparison with standard solid capacitors. In Desktop PCs and notebook computers, the motherboard cooling and monitoring solutions are usually based on
Super I/O Super I/O is a class of I/O controller integrated circuits that began to be used on personal computer motherboards in the late 1980s, originally as add-in cards, later embedded on the motherboards. A super I/O chip combines interfaces for a varie ...
or Embedded Controller.


Bootstrapping using the Basic Input/Output System

Motherboards contain a ROM (and later EPROM, EEPROM, NOR flash) to initialize hardware devices, and loads an operating system from the peripheral device. Microcomputers such as the Apple II and IBM PC used Read-only memory, ROM chips mounted in sockets on the motherboard. At power-up, the central processor unit would load its program counter with the address of the Boot ROM and start executing instructions from the Boot ROM. These instructions initialized and tested the system hardware, displays system information on the screen, performed random-access memory, RAM checks, and then loaded an operating system from a peripheral device. If none was available, then the computer would perform tasks from other ROM stores or display an error message, depending on the model and design of the computer. For example, both the Apple II and the original IBM PC had Cassette BASIC (ROM BASIC) and would start that if no operating system could be loaded from the floppy disk or hard disk. Most modern motherboard designs use a
BIOS In computing, BIOS (, ); an acronym for Basic Input/Output System and also known as the System BIOS, ROM BIOS or PC BIOS) is firmware used to perform Computer hardware, hardware initialization during the booting process (power-on startup), and t ...

BIOS
, stored in an EEPROM or NOR flash chip soldered to or socketed on the motherboard, to Booting, boot an operating system. When the computer is powered on, the BIOS firmware tests and configures memory, circuitry, and peripherals. This Power-On Self Test (POST) may include testing some of the following things: * Video card * Expansion cards inserted into slots, such as conventional PCI and PCI Express * Historical floppy drive * Temperatures, voltages, and fan speeds for hardware monitoring * CMOS memory used to store
BIOS In computing, BIOS (, ); an acronym for Basic Input/Output System and also known as the System BIOS, ROM BIOS or PC BIOS) is firmware used to perform Computer hardware, hardware initialization during the booting process (power-on startup), and t ...

BIOS
configuration * Keyboard (computing), Keyboard and computer mouse, Mouse * Sound card * Network adapter * Optical drives: CD-ROM or DVD-ROM * Hard disk drive and solid state drive * Security devices, such as a fingerprint reader *
USB Universal Serial Bus (USB) is an industry standard ''Industry Standard'' is a 1982 album by Dixie Dregs, The Dregs. It is their only album featuring vocals (by Alex Ligertwood of Santana (band), Santana and Patrick Simmons of The Doobie Brot ...

USB
devices, such as a USB mass storage device Many motherboards now use a successor to BIOS called UEFI. It became popular after Microsoft began requiring it for a system to be certified to run Windows 8.


See also

* Peripheral Component Interconnect (PCI) ** PCI-X ** PCI Express (PCIe) * Accelerated Graphics Port (AGP) * M.2 * Computer case screws * CMOS battery * Expansion card * List of computer hardware manufacturers * Basic Input/Output System (BIOS) * Unified Extensible Firmware Interface (UEFI) * Overclocking * Single-board computer * Switched-mode power supply applications * Symmetric multiprocessing


References


External links


The Making of a Motherboard: ECS Factory Tour



Front Panel I/O Connectivity Design Guide
- v1.3 (pdf file) {{Authority control Motherboard IBM PC compatibles