Types of CPU Socketsby Laura Gittins
The CPU socket locks the central processing unit into place, preventing it from moving or being damaged. It also establishes the connection between the CPU and board so data can transfer to the CPU for processing and return. Different models and types of computers require different types of CPU sockets, as not all CPUs are compatible with every kind of socket. The main difference between CPU sockets is how and where they connect to CPUs.
A pin grid array (PGA) socket is usually a square package made up of a number of holes in an array. The CPU itself has the pins that insert into the socket. The arrangement of pins on the CPU must correspond to the slots on the socket; if not, the CPU will not connect properly to the board. To secure a CPU into a PGA socket, you have to press down until spring contacts lock it -- however, if you do not line up the pins properly, you may bend or damage them.
A zero insertion force (ZIF) socket is an extension of a PGA socket, with pins on the CPU. With a ZIF socket, you don’t have to press down on the CPU to lock it in place. Instead, you simply place the CPU into the socket, then lock it in using a lever or slider on the side of the socket. This results in less risk of you damaging the CPU when you try to insert or remove it from the socket.
A land grid array (LGA) socket is essentially the opposite of a PGA socket. Instead of having the pins connected to the CPU, they’re connected to the socket itself while the CPU has slots with connectors. To lock a CPU into an LGA socket, you have to line up the pins and apply a small amount of pressure. LGA sockets are less fragile overall than PGA sockets, and you can also solder down the package using surface mount technology.
A ball grid array (BGA) is another variant on the PGA socket -- but instead of pins, a BGA socket has copper pads which that are soldered to the package. This means that you do not have to worry about damaging any of several hundred pins, especially as pin-chip architecture designs CPUs with pins closer and closer together. This also means there's less distance for data to travel, so there's less of a chance that the signals will distort.
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