In computer hardware, a CPU socket or CPU slot contains one or more mechanical components providing mechanical and electrical connections between a

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...

and a printed circuit board (PCB). This allows for placing and replacing the

central processing unit A central processing unit (CPU), also called a central processor, main processor or just Processor (computing), processor, is the electronic circuitry that executes Instruction (computing), instructions comprising a computer program. The CPU per ...

(CPU) without soldering. Common sockets have retention clips that apply a constant force, which must be overcome when a device is inserted. For chips with many pins,

zero insertion force Zero insertion force (ZIF) is a type of IC socket or electrical connector that requires very little (but not literally zero) force for insertion. With a ZIF socket, before the IC is inserted, a lever or slider on the side of the socket is move ...

(ZIF) sockets are preferred. Common sockets include Pin Grid Array (PGA) or Land Grid Array (LGA). These designs apply a compression force once either a handle (PGA type) or a surface plate (LGA type) is put into place. This provides superior mechanical retention while avoiding the risk of bending pins when inserting the chip into the socket. Certain devices use

Ball Grid Array A ball grid array (BGA) is a type of surface-mount packaging (a chip carrier) used for integrated circuits. BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be pu ...

(BGA) sockets, although these require soldering and are generally not considered user replaceable. CPU sockets are used on the motherboard in

desktop A desktop traditionally refers to: * The surface of a desk (often to distinguish office appliances that fit on a desk, such as photocopiers and printers, from larger equipment covering its own area on the floor) Desktop may refer to various compu ...

and server computers. Because they allow easy swapping of components, they are also used for prototyping new circuits. Laptops typically use surface-mount CPUs, which take up less space on the motherboard than a socketed part. As the pin density increases in modern sockets, increasing demands are placed on the printed circuit board fabrication technique, which permits the large number of signals to be successfully routed to nearby components. Likewise, within the chip carrier, the

wire bonding Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC ...

technology also becomes more demanding with increasing pin counts and pin densities. Each socket technology will have specific

reflow soldering Reflow soldering is a process in which a solder paste (a sticky mixture of powdered solder and flux) is used to temporarily attach one or thousands of tiny electrical components to their contact pads, after which the entire assembly is subjec ...

requirements. As CPU and memory frequencies increase, above 30 MHz or thereabouts, electrical signalling increasingly shifts to

differential signaling Differential signalling is a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conduc ...

over parallel buses, bringing a new set of signal integrity challenges. The evolution of the CPU socket amounts to a coevolution of all these technologies in tandem. Modern CPU sockets are almost always designed in conjunction with a

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 ...

mounting system, or in lower power devices, other thermal considerations.

Function

A CPU socket is made of plastic, and often comes with a lever or latch, and with metal contacts for each of the pins or lands on the CPU. Many packages are keyed to ensure the proper insertion of the CPU. CPUs with a PGA (pin grid array) package are inserted into the socket and, if included, the latch is closed. CPUs with an LGA (land grid array) package are inserted into the socket, the latch plate is flipped into position atop the CPU, and the lever is lowered and locked into place, pressing the CPU's contacts firmly against the socket's lands and ensuring a good connection, as well as increased mechanical stability.

List of CPU sockets and slots

80x86

Table legend:

Other ISAs

Slotkets

Slotkets are special adapters for using socket processors in bus-compatible slot motherboards.

References

External links

Socket ID Guide

CPU Sockets Chart
- A fairly detailed table listing x86 Sockets and associated attributes.
techPowerUp! CPU Database

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