Editing Computer cooling (section)

====Performance of fans in chassis====
[[File:Chassis-plans-fan-curve.jpg|thumb|Typical fan and [[chassis impedance]] curves]]A computer has a certain resistance to air flowing through the chassis and components. This is the sum of all the smaller impediments to air flow, such as the inlet and outlet openings, air filters, internal chassis, and electronic components. Fans are simple air pumps that provide pressure to the air of the inlet side relative to the output side. That pressure difference moves air through the chassis, with air flowing to areas of lower pressure.

Fans generally have two published specifications: free air flow and maximum differential pressure. Free air flow is the amount of air a fan will move with zero back-pressure. Maximum differential pressure is the amount of pressure a fan can generate when completely blocked. In between these two extremes are a series of corresponding measurements of flow versus pressure which is usually presented as a graph. Each fan model will have a unique curve, like the dashed curves in the adjacent illustration.<ref>{{Cite web|title = Cooling and Noise in Rugged Industrial Computers|url = http://www.chassis-plans.com/white_paper_cooling_and_noise.html|website = Chassis Plans Rugged Computers and LCD Displays|access-date = 2016-02-11|language = en-US|archive-url = https://web.archive.org/web/20140107184852/http://www.chassis-plans.com/white_paper_cooling_and_noise.html|archive-date = 7 January 2014|url-status = live}}</ref>