Information about cleaning computer components
http://www.computerhope.com/cleanin...
http://www.wiscocomputing.com/artic...
http://www.librarysupportstaff.com/...
http://www.bleepingcomputer.com/tut...
http://pcgyaan.wordpress.com/2009/0...
Getting The Grunge Out Of Your PC, Fred Langa cleans the dirtiest PC he can find, and along the way shows you how you can easily tackle yours.
http://www.informationweek.com/stor...
http://www.informationweek.com/stor...
http://www.informationweek.com/stor...
http://www.informationweek.com/stor...
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http://www.informationweek.com/stor...
http://www.informationweek.com/stor...
Quiet noisy computer fans with a drop of oil
http://techrepublic.com.com/5100-62...
How long has it been since you cleaned out your PC? I suggest using an air compressor or can of air and blowing it out. If that doesn't fix it sometimes the BIOS settings allow you to modify you fan settings. Could ultimately come down to a faulty fan.
Most of the time the fan has gone bad. You can usually try to spin the fan (carefully) by your finger. It should spin freely but I suspect it will be either stuck or hard to spin. 1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.