PC components produce a lot of waste heat, and without sufficient cooling will overheat, shutting down or damaging your system. Watercooling provides the ultimate in cooling and aesthetics.
This category contains a huge variety of replacement reservoir tanks. The reservoir stores extra coolant in the loop and helps separate air bubbles from the coolant as it passes through. This is important as excess air bubbles will reduce the effectiveness of the waterblocks, radiator and pump, leading to increased temperatures and unnecessary noise. Most reservoirs are made of transparent plastic so you can see the coolant, and are available in a wide variety of shapes, sizes and finishes, including RGB lighting.