Cpu cooling refers to the methods used to keep the central processing unit (CPU) in a computer cool enough to operate safely. It is important to maintain adequate CPU temperature levels, because high temperatures damage semiconductor components and reduce their operating speeds. In addition, high temperatures cause thermal throttling, which limits the performance of the CPU.

The stock CPU coolers included with a computer are usually adequate for most users. However, enthusiasts or users with demanding applications may prefer an aftermarket solution. For example, a noise-conscious user may want to replace the CPU’s stock fan with one that is optimized for low levels of vibration and noise. Users who plan on overclocking their CPUs also often opt for an aftermarket CPU cooler that is better suited to handling the extra heat generated by higher-speed processors.

Various types of cooling are available, including air and liquid. Liquid cooling systems use a system similar to the radiator in a car or home, circulating a fluid through “water blocks” that rest on top of the CPU. The relatively cooler liquid circulating in the water block pools away heat from the CPU, which is then cooled by fans that expose it to cold air. The cooled liquid is then returned to the water block, and the cycle repeats.

A less common method of cooling uses a phase-change cooler. These devices consist of a box that sits underneath the PC, with a tube leading to the CPU. The box contains a compressor the same type that would be found in a freezer, which compresses a gas mixture to condense it into liquid. The liquid flows into the CPU’s evaporator, which is usually an expansion device that could be anything from a capillary tube to a more elaborate thermal expansion valve. As the liquid evaporates, it pulls heat from the CPU.