the average desktop. They also generate a significant amount of noise, since they are essentially refrigerators; however, the compressor choice and air cooling system is the main determinant of this, allowing for flexibility for noise reduction based on the parts chosen. A "thermosiphon" traditionally refers to a closed system consisting of several pipes and/or chambers, with a larger chamber containing a small reservoir of liquid (often having a boiling point just above ambient temperature, but not necessarily). The larger chamber is as close to the heat source and designed to conduct as much heat from it into the liquid as possible, for example, a CPU cold plate with the chamber inside it filled with the liquid. One or more pipes extend upward into some sort of radiator or similar heat dissipation area, and this is all set up such that the CPU heats the reservoir and liquid it contains, which begins boiling, and the vapor travels up the tube(s) into the radiator/heat dissipation area, and then after condensing, drips back down into the reservoir, or runs down the sides of the tube. This requires no moving parts, and is somewhat similar to a heat pump, except that capillary action is not used, making it potentially better in some sense (perhaps most importantly, better in that it is much easier to build, and much more customizable for specific use cases and the flow of coolant/vapor can be arranged in a much wider variety of positions and distances, and have far greater thermal mass and maximum capacity compared to heat pipes which are limited by the amount of coolant present and the speed and flow rate of coolant that capillary action can achieve with the wicking used, often sintered copper powder on the walls of the tube, which have a limited flow rate and capacity.) Liquid nitrogen As liquid nitrogen boils at , far below the freezing point of water, it is valuable as an extreme coolant for short overclocking sessions. In a typical installation of liquid nitrogen cooling, a copper or aluminium pipe is mounted on top of the processor or graphics card. After the system has been heavily insulated against condensation, the liquid nitrogen is poured into the pipe, resulting in temperatures well below . Evaporation devices ranging from cut out heatsinks with pipes attached to custom milled copper containers are used to hold the nitrogen as well as to