Datasheet

Identifying Purposes and Characteristics of Cooling Systems 77
Liquid Cooling
Liquid cooling is a technology whereby a special water block is used to conduct heat away
from the processor (as well as from the chipset). Water is circulated through this block to a
radiator, where it is cooled.
The theory is that you could achieve better cooling performance through the use of
liquid cooling. For the most part, this is true. However, with traditional cooling methods
(which use air and water), the lowest temperature you can achieve is room temperature.
Plus, with liquid cooling, the pump is submerged in the coolant (generally speaking), so as
it works, it produces heat, which adds to the overall liquid temperature.
The main benefit to liquid cooling is silence. There is only one fan needed: the fan on the
radiator to cool the water. So a liquid-cooled system can run extremely quietly.
Liquid cooling, while more efficient than air cooling and much quieter, has its drawbacks.
Most liquid-cooling systems are more expensive than supplemental fan sets, and require less
familiar components, such as reservoir, pump, water block(s), hose, and radiator.
The relative complexity of installing liquid cooling systems, coupled with the perceived
danger of liquids in close proximity to electronics, leads most computer owners to consider
liquid cooling a novelty or a liability. The primary market for liquid cooling is the high-
performance niche that engages in overclocking to some degree. However, developments in
active air cooling, including extensive piping of heat away from the body of the heat sink,
have kept advanced cooling methods out of the forefront.
Heat Pipes
Heat pipes are closed systems that employ some form of tubing filled with a liquid suitable
for the applicable temperature range. Pure physics are used with this technology to achieve
cooling to ambient temperatures; no outside mechanism is used. One end of the heat pipe is
heated by the component being cooled. This causes the liquid at the heated end to evaporate
and increase the relative pressure at that end of the heat pipe with respect to the cooler end.
This pressure imbalance causes the heated vapor to equalize the pressure by migrating to the
cooler end, where the vapor condenses and releases its heat, warming the nonheated end of
the pipe. The cooler environment surrounding this end transfers the heat away from the pipe
by convection. The condensed liquid drifts to the pipe’s walls and is drawn back to the heated
end of the heat pipe by gravity or by a wicking material or texture that lines the inside of the
pipe. Once the liquid returns, the process repeats.
Peltier Cooling Devices
Water- and air-cooling devices are extremely effective by themselves, but they are more
effective when used with a device known as a Peltier cooling element. These devices, also
known as thermoelectric coolers (TECs), facilitate the transfer of heat from one side of
the element, made of one material, to the other side, made of a different material. Thus,
they have a hot side and a cold side. The cold side should always be against the CPU sur-
face, and optimally, the hot side should be mated with a heat sink or water block for heat
dissipation. Consequently, TECs are not meant to replace air-cooling mechanisms but to
complement them.
86498book.indb 77 7/22/09 5:37:59 AM