In a computer, water cooling or liquid cooling is a system used to reduce the temperature of its hardware, specifically the CPU and GPU. Liquid is more efficient than gas at conducting thermal energy, so liquid-cooled machines maintain desired operating temperatures better than their air-cooled counterparts.
Typically, water cooling systems use deionized or distilled water, as the minerals found in water from other sources can reduce its ability to lower temperatures. Because this can still damage electronics, liquid cooling systems must be used with caution. If any water leaks from the cooling system, it can destroy your hardware.
How it works
The process begins with a pump that sends water to a water block, which replaces the heat sink in a traditional fan setup. As water absorbs thermal energy, it's passed to a heat exchange (usually a radiator) where a fan blows the heat out of the computer, and the cycle starts again.