The brains of your computer perform millions of calculations per second, but they also generate a lot of heat. If not properly dissipated, that heat can damage delicate electronics inside the computer and cause a system failure. A CPU cooler is necessary to keep the temperature of your processor low enough to prevent overheating and prolong the life of your processor.

A basic air CPU cooler works by passing cool air over the hot CPU and using a fan to force that air through small holes in the CPU cooler. As the warm air passes over the hot processor, it cools slightly and then is pulled by the fan to continue cooling the CPU.

Alternatively, liquid cooling systems use liquid to cool the CPU instead of air. The cooler uses a series of pipes, some of which connect to the CPU, others to the radiator located in the back of your system case. The liquid is circulated by a fan, which draws cooler liquid in through one side of the heat sink and sends it out through the other. The cooled liquid is then sent to the radiator and pumped back through the system.

When choosing a CPU cooler, it is important to consider the thermal design power (TDP) of your CPU. A CPU cooler must be rated for the processor it is designed to cool, and while a heatsink that fits a 2.8 GHz Northwood core Pentium 4 may physically work with the processor, it will be grossly insufficient for the much hotter-running Prescott core. Cpu cooling