One of the most important components of a computer is the CPU, as it is the component which processes all of the data for every program. The CPU plugs into the CPU socket on the computer's motherboard, locking it in place and connecting it to every other component of the computer. Intel and AMD, the two leading producers of computer CPU's, each have several different CPU designs which can be used in computers; as a result there are several different CPU sockets that you may find on motherboards. As a CPU cannot be used without the correct type of socket, matching the CPU to the motherboard's socket is essential to building or upgrading a computer.
Purpose of CPU Sockets
The CPU socket on a motherboard serves two purposes. The first is to allow the transfer of data to and from the CPU. Pins attached to either the CPU or to the socket itself, connect the internal processing components of the CPU to the circuit connections, contained within the CPU socket. These connections allow data from every component on the motherboard to be sent to the CPU for processing and return.
The second purpose of a CPU socket is to protect the CPU and computer from damage. Once a CPU has been inserted into the socket, the socket is closed. Closing the socket locks the CPU in place, preventing it from moving or being removed from the CPU socket until it has been unlocked. If the CPU were able to move, short circuits or damage to the pins which allow data transfer might occur.
PGA sockets support the use of CPU's that feature a Pin Grid Array architecture. With PGA CPU's, the connecting pins are mounted within the CPU and plug into corresponding holes in the socket to allow the CPU to connect to the motherboard's circuits. The number of pins on the CPU will vary depending on the type of socket that the particular CPU uses, and will be arranged in a specific pattern so that the CPU will only be able to plug into the socket in one direction.
Some PGA sockets use a method known as ZIF or "Zero Insertion Force" in which the CPU can be plugged in without having to press it into place; the locking of the socket closes the holes around the pins to make contact. This was created to solve the problem of pins being bent while attempting to insert CPU's.
LGA sockets support the use of CPU's that feature a Land Grid Array architecture. With LGA CPU's, the connecting pins are mounted within the socket and the CPU features a grid of connectors which lay onto the pins. Locking the CPU into the socket is done in such a way that it places a small amount of downward force on the CPU, ensuring a good connection with the pins.
Intel Socket Types
Intel has created a number of sockets to support product lines such as their Pentium series', Core2 series, and the i7 series of processors. As Intel processors have become more advanced, the number of pins on the processors have increased and older socket types have become incompatible with new CPU's. The most common Intel sockets that are still in use include Socket 478 for the Pentium IV and Celeron processors, Sockets 771 and 775 for the Pentium D, Celeron D, and the Core2 Duo and Quad processors, and Socket 1366 for the Core i7 product line.
AMD Socket Types
AMD has created several socket types as well, though many of their sockets are backwards-compatible with previous CPU types due to similar CPU architecture across several product lines. The most common AMD sockets that are still in use include Socket A for the Athalon and Duron CPU's, Socket AM2 for the Athalon 64 and Semperon processors, Socket AM2+ for the Phenom and Athalon 64 product lines, and Socket F for the Opteron and Athalon 64 7x processors.