CPUs must maintain a low temperature in order to operate. All CPUs must have a cooling mechanism (called a heatsink) attached so they can function. Heatsinks sit directly on top of the CPU – separated only by a thin layer of thermal paste – and dissipate the heat that the CPU generates. Some heatsinks use liquid cooling, so they contain liquids that stay cold even in warm situations. Liquid cooling is completely safe, and in many cases, it’s more effective than traditional heatsinks, although liquid-cooling heatsinks are typically more expensive than traditional ones.