The components inside a computer's case, especially integrated circuits or chips, generate heat as a by-product. A build up of heat can be devastating to integrated circuits, which normally have a long life expectancy. For that reason, a combination of fans and heat sinks are used to remove excess heat from inside a computer. A technique called "overclocking" runs CPUs at faster speeds than normal. When overclocking is used, standard CPU fans may not be sufficient in removing heat. There are special high-performance CPU fans available to use in these situations. CPU fans may be thermal controlled. When the CPU's heat reaches a certain temperature, the fan can be automatically turned on (and off).
There are different types of CPU chips, and CPU fans are designed for use with specific chips. CPU fan specifications include a parameter called "socket type." The fan must match the correct socket type.