cpu sockets

Starting with the 486 processor all PC processors started to be “socketed” instead of being soldered directly to the motherboard. Since then both Intel and AMD have been creating several different sockets and slots to be used by their processors. In this tutorial we will list all socket and slot types released to date with their respective pinouts, also giving examples of compatible CPUs.
Up to the 386 processor almost all CPUs were soldered directly to the motherboard. There were socket-based Intel 386 CPUs, but CPU upgrade was a very rare procedure among users and even among technicians. So up to that time if you wanted to install a faster CPU you would have to replace the motherboard as well.
This story changed with the launching of the 486 processor and the massive use of ZIF (Zero Insertion Force) socket, also known as LIF (Low Insertion Force), which has a lever that installs and removes the CPU from the socket without the need of the user or the technician to press the CPU down in order to be installed on the socket. The use of this socket lowered a lot the chances of breaking or bending the CPU pins during its installation or removal. The use of the same pinout by more than one processor allowed the user or the technician to install different processor models on the same motherboard by just removing the old CPU and installing the new one. Of course the motherboard needed to be compatible with the new CPU being installed and also properly configured.
Since the 486 processor times both Intel and AMD have been developing a series of sockets and slots to be used by their CPUs.
The socket created to be used together with the very first 486 processor wasn’t ZIF and didn’t allow you to replace the CPU with a different processor model. Even though this socket didn’t have an official name, let’s call it socket 0. After socket 0 Intel released socket 1, which had the same pinout of socket 0 with the addition of a key pin. It also adopted ZIF standard, allowing the installation of several different processor types on the same socket (i.e. on the same motherboard). Other socket standards were released for the 486 family after socket 1 – socket 2, socket 3 and socket 6 – in order to increase the number of CPU models that could be installed on the CPU socket. Thus socket 2 accepts the same CPUs accepted by socket 1 plus some more models, and so on. Even though socket 6 was designed, it was never used. Thus we usually call the pinout used by 486-class processors as “socket 3”. Intel called “overdrive” the possibility of a socket to accept more than one CPU model. Intel also adopted this name on CPUs that used a pinout from an older CPU, in order to allow it to be installed on an older motherboard.
The first Pentium processors (60 MHz and 66 MHz) used a pinout standard called socket 4, which was fed with 5 V. Pentium processors from 75 MHz on were fed with 3.3 V and thus required a new socket, called socket 5, which was incompatible with socket 4 (a Pentium-60 couldn’t be installed on socket 5 and a Pentium-100 couldn’t be installed on socket 4, for example). Socket 7 uses the same pinout as socket 5 with the addition of one key pin, accepting the same processors accepted by socket 5 plus new CPUs, especially CPUs designed by competing companies (the real difference between socket 5 and socket 7 is that while socket 5 always fed the CPU with 3.3 V, socket 7 allowed the CPU to be fed with a different voltage level, like 3.5 V or 2.8 V, for example). Super 7 socket is a socket 7 capable of running up to 100 MHz, used by AMD CPUs. We usually call the Pentium Classic and compatible CPUs pinout as “socket 7”.
As you may notice, sockets and pinouts at this stage were very confusing, as a given processor could be installed on different socket types. A 486DX-33 could be installed on sockets 0, 1, 2, 3 and, if it were released, 6.
For the next CPUs manufacturers followed a simpler scheme, where each CPU could be installed only on just one socket type.
On the table below we list all socket and slot types created by Intel and AMD since the 486 CPU and examples of CPUs compatible with them.
Socket
Pin Count
Example of Compatible CPUs
Pinout
Socket 0
168
486 DX
Pinout
Socket 1
169
486 DX
486 DX2
486 SX
486 SX2
Pinout
Socket 2
238
486 DX
486 DX2
486 SX
486 SX2
Pentium Overdrive
Pinout
Socket 3
237
486 DX
486 DX2
486 DX4
486 SX
486 SX2
Pentium Overdrive
5x86
Pinout
Socket 4
273
Pentium-60 and Pentium-66
Pinout
Socket 5
320
Pentium-75 to Pentium-133
Pinout
Socket 6
235
486 DX
486 DX2
486 DX4
486 SX
486 SX2
Pentium Overdrive
5x86
(Never Used)
Socket 7
321
Pentium-75 to Pentium-200
Pentium MMX
K5
K6
6x86
6x86MX
MII
Pinout
Socket Super 7
321
K6-2
K6-III
Pinout
Socket 8
387
Pentium Pro
Pinout
Socket 370
370
Celeron
Pentium III FC-PGA
Cyrix III
C3
Pinout
Socket 423
423
Pentium 4
Pinout
Socket 463
463
Nx586
Pinout
Socket 478
478
Pentium 4
Celeron
Celeron D
Celeron M
Core Duo
Core Solo
Pentium 4 Extreme Edition
Pentium M
Mobile Pentium III
Mobile Celeron
Mobile Pentium 4
Pinout
Socket 479(Socket M)
479
Core Duo
Core Solo
Pentium M
Mobile Pentium III
Mobile Celeron
Mobile
Pentium 4
Celeron M
Pinout
Socket 775(LGA775)(Socket T)
775
Pentium 4
Pentium 4 Extreme Edition
Pentium D
Pentium Extreme Edition
Celeron D
Core 2 Duo
Core 2 Extreme
Pinout
Socket 603
603
Xeon
Mobile Pentium 4
Pinout
Socket 604
604
Xeon
Pinout
Socket 771
771
Xeon
Pinout
Socket 418
418
Itanium
Pinout
Socket 611
611
Itanium 2
Pinout
Socket 462(Socket A)
453
Athlon
Duron
Athlon XP
Sempron
Pinout
Socket 754
754
Athlon 64
Sempron
Turion 64
Pinout
Socket 939
939
Athlon 64
Athlon 64 FX
Athlon 64 X2
Opteron
Pinout
Socket 940
940
Athlon 64 FX
Opteron
Pinout
Socket AM2
940
Athlon 64
Athlon 64 FX
Sempron
Athlon 64 X2
Pinout
Socket S1
638
Turion 64 X2
Pinout
Socket F
1,207
Opteron
Pinout
Slot 1
242
Pentium II
Pentium III (Cartridge)
Celeron SEPP (Cartridge)
Pinout
Slot 2
330
Pentium II Xeon
Pentium III Xeon
Pinout
Slot A
242
Athlon (Cartridge)
Pinout