Water coolers are great for cooling, allow extremely high overclocking and are even quieter than conventional CPU fans - at least on paper. Installation, however, represents a bottleneck and is relatively complicated compared to air-cooling due to the number of required components. Then there is the weight factor. Those who frequent LAN parties, for example, don't want to lug around the extra pounds of a pump and the water in the reservoir. For this reason many manufacturers also offer external water cooling systems that allow simple and quick installation. These water coolers can also easily be disconnected from the PC for separate transport.