Since the very first CPU, both Intel and AMD have been creating several different sockets to be used by their processors. In this tutorial, we will list all socket types released to date with a list of compatible CPUs.

In the beginning, a CPU socket was compatible with just one kind of processor. This scenario changed with the launching of the 486 processor and the massive use of ZIF (Zero Insertion Force) sockets, also known as LIF (Low Insertion Force). The ZIF socket 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 for it to be installed on the socket. The use of this socket greatly lowered 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 merely 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 then, 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 as socket 0 with the addition of a key pin. It also adopted the ZIF standard, allowing the installation of several different types of processors 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 in addition to some more models, and so forth. Even though the socket 6 was designed, it was never used. Thus, we usually call the pinout used by 486-class processors as “socket 3.” Originally, Intel defined “overdrive” as the possibility of a socket to accept more than one CPU model. Intel also adopted this name on newer CPUs that used a pinout from an older CPU in order to allow the new CPU 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, requiring a new socket, called socket 5, which was incompatible with socket 4. (For example, a Pentium-60 couldn’t be installed on socket 5 and a Pentium-100 couldn’t be installed on socket 4.). 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, such as 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 on just one socket type.

On the next pages, we list all socket types created by Intel and AMD since the 486 CPU, with a list of CPUs compatible with them.

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.