A CPU socket or CPU slot is a connector on a computer's motherboard that accepts a CPU and forms an electrical interface with it. As of 2007, most desktop and server computers, particularly those based on the Intelx86 architecture, include socketed processors. Most CPU-sockets interfaces are based on the pin grid array (PGA) architecture, in which short, stiff pins on the underside of the processor package mate with holes in the socket. To minimize the risk of bent pins, zero insertion force (ZIF) sockets allow the processor to be inserted without any resistance, then grip the pins firmly to ensure a reliable contact after a lever is flipped. As of 2007, several current and upcoming socket designs use land grid array (LGA) technology instead. In this design, it is the socket which contains pins. The pins contact pads or lands on the bottom of the processor package. In the late 1990s, many x86 processors fit into slots, rather than sockets. CPU slots are single-edged connectors similar to expansion slots, into which a PCB holding a processor is inserted. Slotted CPU packages offered two advantages: L2 cache memory could be upgraded by installing an additional chip onto the processor PCB, and processor insertion and removal was often easier. However, slotted packages require longer traces between the CPU and chipset, and therefore became unsuitable as clock speeds passed 500 MHz. Slots were abandoned with the introduction of AMD's Socket A and Intel's Socket 370.
Socket 939 - AMD single-processor socket featuring dual-channel DDR-SDRAM. Supports Athlon 64, Athlon 64 FX to 1 GHz[1], Athlon 64 X2, Opteron 100-series processors (PGA 939 contacts). Superseded by Socket AM2 after about 2 years of launch.
Socket 940 - AMD single and multi-processor socket featuring DDR-SDRAM. Supports AMD Opteron[1] (2xx and 8xx Series), Athlon 64 FX processors (PGA 940 contacts).
Socket A (also known as "Socket 462") - AMD socket supporting Athlon, Duron, Athlon XP, Athlon XP-M, Athlon MP, and Sempron processors (PGA 462 contacts).
Socket AM2 - AMD single-processor socket featuring DDR2-SDRAM. Replaces Socket 754 and Socket 939[1] (PGA 940 contacts, some confused Socket AM2 with "Socket 940" for server processors). Supports Athlon 64, Athlon 64 X2, Athlon 64 FX and Opteron processors.
Socket AM2+ - Future AMD socket for single processor systems. Features support for DDR2 and HyperTransport 3 with separated power lanes. Planned to launch between mid 2007 and Q3 2007. Replaces Socket AM2 (PGA 940 contacts, electrically compatible with Socket AM2).
Socket AM3 - Future AMD socket for single processor systems. Features support for DDR3 and HyperTransport 3 with separated power lanes. Planned to launch mid 2008. Replaces Socket AM2+ with support for DDR3-SDRAM (PGA 940 contacts).
Socket F (also known as "Socket 1207") - AMD multi-processor socket featuring DDR2-SDRAM. Supports AMD Opteron[1](2xxx and 8xxx Series) and Athlon 64 FX processors. Replaces Socket 940 (LGA 1207 contact).
Socket S1 - AMD socket for mobile platforms featuring DDR2-SDRAM. Replaces Socket 754 for mobile processors (PGA 638 contacts).
Future processor which is in development under the Fusion project codename, will employ Socket FS1 and two other sockets.
Socket G3 - successor to socket F+, paired with Socket G3 Memory Extender for servers to install more ememory module to one single processor.
Socket B (LGA 1366 [5]) - a new socket for future Intel CPUs incorporating the integrated memory controller and Intel QuickPath Interconnect.
Socket H (LGA 715) - a future replacement for the current Socket T (LGA 775), without integrated memory controller and newer point-to-point processor interconnect.
Socket J (also known as Socket 771 or LGA 771) - Intel Xeon (Woodcrest core)
Slotkets - adapters for using socket processors in bus-compatible slot motherboards
Notes and References
^ abcd These sockets are for CPUs with integrated memory controllers. The 754 pin models have a single memory channel routed through the CPU pins. The 939 pin models have two memory channels, hence the higher pin count. The 940 pin CPUs also have two memory channels but they require registered memory, and most have support for SMP. Sockets F and AM2 are redesigned to support DDR2. The Socket F contains 1207 pins (Added pins speculated to be for more scalability and better power distribution). Socket AM2 has 940 pin-holes but does not support current AMD Opteron processors.
^ abc The 478 pin socket was introduced because it uses a micro-PGA layout which is physically smaller than the socket 423. Socket 775 was introduced with support for PCI express, DDR2 memory and Intel 64 (Intel's implementation of x86-64), but also moved to the new Land Grid Array physical layout, where the pins are in the socket rather than on the CPU package, for better electrical performance.
