The Big Processor Guide - Sockets

Users like expandability. And that is why most modern systems have a socket into which a removable processor is placed. It certainly isn't because the motherboard makers want it; sockets cost money. And motherboard manufacturers are all about cutting costs. But sockets are here to stay, and so this page will try to cover the majority of those on the market.

AMD

Desktop

Socket AM3: AMD's follow-up to AM2. AM3 processors will support both DDR2 and DDR3 memory, and are expected to be pin-compatible with AM2. The major implication of this is that AM2 is supposed to be forward-compatible with AM3 processors (though apparently not vice-versa). Look for it in 2007.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD AM2 PGA ZIF Pin 940 Desktop HTT On die

Socket AM2: AMD's current desktop and light-server/workstation socket, with support for future Athlon 64 (and X2 and FX) series chips. In addition to having dual-core support, it will bring DDR2 memory support to AMD's desktop lineup. Has 940 pins, but is not physically compatible with Socket 940. Support for some Athlon 64s, Athlon 64 X2s, Semrpons, and Opterons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD AM2 PGA ZIF Pin 940 Desktop HTT On die

Socket 939: Support for some "SledgeHammer" and "San Diego" Athlon 64 FX chips and some ClawHammer, Newcastle, and Venice Athlon 64s. Support for all Winchester and San Diego Athlon 64s and Manchester and Toledo Athlon 64 X2s. Support for certain Opterons. Permits a motherboard with two less layers than Socket 940 (for lower production costs) and the use of unbuffered, non-ECC memory (for lower implementation costs). Dual channel HyperTransport memory controllers integrated into processor. Support for dual-core processors (all Socket 939 motherboards that support the 90 nm Athlon 64s support dual-core). Support for some Athlon 64s, Athlon 64 X2s, a few Semprons, and a few Opterons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD 939 PGA ZIF Pin 939 Desktop HTT On die

Socket 754: Support for some ClawHammer, Newcastle, and Venice Athlon 64s. Support for some Sempron products. Single channel HyperTransport memory controller integrated into processor.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD 754 PGA ZIF Pin 754 Desktop HTT On die

Socket 940: Support for all "SledgeHammer" Opteron and and some Athlon FX processors. Currently being phased out for desktops in favor of Socket 939. Will continue to support Opteron processors. HyperTransport memory controllers integrated into processor. Support for dual-core processors (all Socket 940 motherboards that support 90nm Troy Opterons support dual-core).

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD 940 PGA ZIF Pin 940 Desktop HTT On die

Socket A: Support for Athlon, Duron, Athlon MP, Athlon XP-M Athlon XP, and some Sempron processors. Has 462 pins. 9 of these are blocked (for orienting the processor), so there are 453 actual pins.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD AM2 PGA ZIF Pin 453 Desktop Double-pumped On die

Slot A: Allowed the cheaper addition of L2 cache. Physically but not electrically compatible with Intel's Slot 1.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD Slot A Slot Edge 242 Desktop Double-pumped Off die

Super Socket 7: A super-charged Socket 7. In essence, it extends Socket 7 to have support for faster Front Side Bus speeds. This means Socket 7 processors will work in Super 7 motherboards, but Super 7 processors will not work to their full abilities in Socket 7 motherboards. Support for some K6-2 and all K6-III processors.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD Super 7 PGA ZIF Pin 321 Desktop Normal Motherboard

Laptop

Socket S1: Next-generation socket for laptops, it will bring support for DDR2 memory and dual core processors. It will have 638 pins. Support for future Turion 64 and Turion 64 X2 products. Launch May 19, 2006.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD S1 PGA ZIF Pin 638 Laptop HTT On die

Socket 754: Mobile variant of the desktop socket. Compatible with all Mobile Athlon 64 and DDR-based Turion 64 products.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD 754 PGA ZIF Pin 754 Laptop HTT On die

Socket A: Mobile variant of the desktop socket. Physically identical. Support for Mobile Athlon XP-M and Mobile Duron processors.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD A PGA ZIF Pin 462 Laptop Double-pumped On die

Super Socket 7: Mobile variant of the desktop socket. Support for K6-derived processors.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD Super 7 PGA ZIF Pin 321 Laptop Normal On die

Server

Socket F: Next-generation socket for servers. Expected to support future Opterons, up to quad-core processors, and Fully-Buffered DIMM memory, meaning memory support (initially DDR2) could be expanded for DDR3, XD-RAM, or other technologies. 1207 pins on the motherboard; Socket F will be AMD's first-ever Land Grid Array socket, a decision apparently made on the logic that in the event of damaged pins it is cheaper to replace a motherboard than an Opteron. Support for most Revision F Opterons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD F LGA ZIF Ball 1207 Server HTT On die

Socket 940: Support for most Opteron processors. Has 940 pins.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD 940 PGA ZIF Pin 940 Server HTT On die

Socket A: Support for Athlon MP series. Identical to desktop socket.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
AMD A PGA ZIF Pin 462 Server Double-pumped On die

Intel

Desktop

Socket T: AKA LGA 775 or just Socket 775. The first consumer LGA socket. Support for late-model Pentium 4, Pentium D, Pentium 4 Extreme Edition, and Pentium Extreme Edition. Support for desktop Core 2 Duo and Core 2 Extreme.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel T LGA ZIF Ball 775 Desktop Quad-pumped On die

Socket 478: Support for Northwood Pentium 4s.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 478 PGA ZIF Pin 478 Desktop Quad-pumped On die

Socket 423: The short-lived socket that housed only the Pentium 4 Willamette. It was quickly scrapped for performance reasons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 423 PGA ZIF Pin 423 Desktop Quad-pumped On die

Socket 370: First introduced for use by Celerons that had no need for the Slot form factor. Support for some Celerons and Pentium IIIs.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 370 PGA ZIF Pin 370 Desktop Normal On die

Slot 1: Introduced to allow the cheaper use of L2 cache. Support for Pentium IIs, some Pentium IIIs, and some Celerons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel Slot 1 Slot Edge 242 Desktop Normal Off die

Laptop

Socket P: Upcoming replacement for Socket M. Core 2 Merom will move to this socket in order to support a faster Front Side Bus. The change is expected in the first half of 2007.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel P PGA ZIF Pin 478 Laptop Quad-pumped On die

Socket 479: Support for Pentium M and Core Solo/Duo processors, as well as the Xeon Sossaman. Please note, two versions exist with slightly different pin arrangements. One supports Pentium M, one supports Core (and Sossaman). They are absolutely, positively, not compatible. This was done because the two series require different chipsets. The later version is officially refered to as FCPGA6, and sometimes unofficially refered to as Socket M For the purposes of this guide, the name Socket M is used to distinguish between the two versions.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 479 PGA ZIF Pin 478 Laptop Quad-pumped On die

Socket 478: Support for the Pentium 4-M.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 478 PGA ZIF Pin 478 Laptop Quad-pumped On die

Socket 370: Support for the Mobile Pentium III.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 370 PGA ZIF Pin 370 Laptop Normal On die

Socket 7: Support for the mobile version of the Pentium MMX.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 7 PGA ZIF Pin 321 Laptop Normal On die

Server

Socket J: Socket for Dempsey and later Xeons. Similar to Socket T.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel J LGA ZIF Ball 771 Server Quad-pumped On die

Socket 604: Updated form of Socket 603. Analogous to Socket 423/478. Support for many Xeons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 604 PGA ZIF Pin 604 Server Quad-pumped On die

Socket 603: Server analog to Socket 370. Support for some Xeons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 603 PGA ZIF Pin 603 Server Quad-pumped On die

Slot 2: Server analog to Slot 1. Support for many Xeons.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel Slot 2 Slot Edge 330 Server Normal Off die

Socket 8: Server analog to Socket 7. Support for Pentium Pro and Pentium II Overdrive.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Intel 8 PGA ZIF Pin 387 Server Normal On die

Shared

Desktop

Socket 7: An expanded Socket 5. Backwards compatible with Socket 5, so that a Socket 5 processor may be used in a Socket 7 motherboard. Added one pin (a disconnected "key" pin to ensure it was not physically possible to place a Socket 7 processor in a Socket 5 motherboard) and the ability to provide split supply voltages, where Socket 5 could supply only a single voltage.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Shared 7 PGA ZIF Pin 321 Desktop Normal Motherboard

Socket 5: The first Staggered Pin Grid Array, wherein the rows of pins are offset (rather than all on the same grid) so that more pins can be fit into less space. Also, more significantly, the first Zero Insertion Force socket.

Manufacturer Socket Type Contact Type Contact Count Class Bus L2
Shared 5 PGA ZIF Pin 320 Desktop Normal Motherboard

Key

This section is a guide to some of the terms used above: what they mean, why they matter, etc.

Bus types
Several general groupings of bus have been implemented over the years. For simplicity, this page classifies each socket according to the sort of bus used. HTT has been used here to refer to HyperTransport Technology. A "normal" bus is a standard front-side bus, single-pumped. Doubled-pumped and quad-pumped buses operate at twice and four times the actual Front Side Bus clock speed, respectively.
LGA
Land Grid Array. Sockets where the motherboard has a series of pins meant to connect to balls on the bottom of the processor.
PGA
Pin Grid Array. Sockets where the motherboard has a series of holes into which pins on the base of the processor are inserted.
Slot
Similar to a PCI, AGP, or PCI-Express slot. The motherboard has a slot that the processor (usually in a cartridge form factor) plugs in. The processor has a series of contact points that connect to the motherboard. Slots offer one key advantage: the ability to move L2 cache off of the motherboard and on to a dedicated PCB attached directly to the processor itself. This is also cheaper and easier than implementing the cache "on die": that is, putting it on the same piece of silicion as the processor's core. However, this "off die" cache is operated at a lower frequency than the processor itself, which reduces performance.
Socket
Usually a squarish connection point the processor is placed in.
ZIF
Zero Insertion Force. This refers to sockets that do not use a "friction fit" to hold the processor in place. Instead they have a lever that is used to "close" the socket. The socket itself is generally made of two pieces, one of which slides laterally as the lever moves. This helps to "grip" the processor. The heatsink is then affixed to help keep the processor stationary.