page_title: Computer cooling
section_title: Liquid cooling
hierarchical_section_title: Computer cooling / Other techniques / Liquid cooling
caption_attribution_description: English: A watercooled PC. The hose is secured to hose barb fittings with screw/band hose clamps. In the lower left is a D5 pump made by Laing GmbH, part of ITT Corporation. From there, coolant flows vertically to the water block on the CPU, then right to the radiator (not visible), then back to the pump. The hose rising vertically to the top of the picture is a T Line used to fill and empty the coolant loop. Deutsch: Ein wassergekühlter PC
context_page_description: Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units, chipset, graphics cards, and hard disk drives.
  Components are often designed to generate as little heat as possible, and computers and operating systems may be designed to reduce power consumption and consequent heating according to workload, but more heat may still be produced than can be removed without attention to cooling. Use of heatsinks cooled by airflow reduces the temperature rise produced by a given amount of heat. Attention to patterns of airflow can prevent the development of hotspots. Computer fans are widely used along with heatsink fans to reduce temperature by actively exhausting hot air. There are also more exotic cooling techniques, such as liquid cooling. All modern day processors are designed to cut out or reduce their voltage or clock speed if the internal temperature of the processor exceeds a specified limit.
context_section_description: Liquid cooling is a highly effective method of removing excess heat, with the most common heat transfer fluid in desktop PCs being (distilled) water. The advantages of water cooling over air cooling include water's higher specific heat capacity and thermal conductivity.
  The principle used in a typical (active) liquid cooling system for computers is identical to that used in an automobile's internal combustion engine, with the water being circulated by a water pump through a waterblock mounted on the CPU (and sometimes additional components as GPU and northbridge) and out to a heat exchanger, typically a radiator. The radiator is itself usually cooled additionally by means of a fan. Besides a fan, it could possibly also be cooled by other means, such as a Peltier cooler (although Peltier elements are most commonly placed directly on top of the hardware to be cooled, and the coolant is used to conduct the heat away from the hot side of the Peltier element). A coolant reservoir is often also connected to the system.
  Besides active liquid cooling systems, passive liquid cooling systems are also sometimes used. These systems often discard a fan or a water pump, hence theoretically increasing the reliability of the system, and/or making it quieter than active systems. Downsides of these systems however are that they are much less efficient in discarding the heat and thus also need to have much more coolant -and thus a much bigger coolant reservoir- (giving more time to the coolant to cool down).
  Liquids allow the transfer of more heat from the parts being cooled than air, making liquid cooling suitable for overclocking and high performance computer applications. Compared to air cooling, liquid cooling is also influenced less by the ambient temperature. Liquid cooling's comparatively low noise-level compares favorably to that of air cooling, which can become quite noisy.
  Disadvantages of liquid cooling include complexity and the potential for a coolant leak. Leaked water (or more importantly any additives added to the water) can damage any electronic components with which it comes into contact, and the need to test for and repair leaks makes for more complex and less reliable installations.  (Notably, the first major foray into the field of liquid-cooled personal computers for general use, the high-end versions of Apple's Power Mac G5, was ultimately doomed by a propensity for coolant leaks.) An air-cooled heat sink is generally much simpler to build, install, and maintain than a water cooling solution, although CPU-specific water cooling kits can also be found, which may be just as easy to install as an air cooler. These are not limited to CPUs, however, and liquid cooling of GPU cards is also possible.
  While originally limited to mainframe computers, liquid cooling has become a practice largely associated with overclocking in the form of either manufactured kits, or in the form of do-it-yourself setups assembled from individually gathered parts. The past few years have seen an increase in the popularity of liquid cooling in pre-assembled, moderate to high performance, desktop computers. Sealed ("closed-loop") systems incorporating a small pre-filled radiator, fan, and waterblock simplify the installation and maintenance of water cooling at a slight cost in cooling effectiveness relative to larger and more complex setups.
  Liquid cooling is typically combined with air cooling, using liquid cooling for the hottest components, such as CPUs or GPUs, while retaining the simpler and cheaper air cooling for less demanding components.
  The IBM Aquasar system uses hot water cooling to achieve energy efficiency, the water being used to heat buildings as well.
  Since 2011, the effectiveness of water cooling has prompted a series of all-in-one (AIO) water cooling solutions. AIO solutions result in a much simpler to install unit, and most units have been reviewed positively from review sites.
caption: DIY water cooling setup showing a 12 V pump, CPU waterblock and the typical application of a T-Line
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