# Computer fan question **URL:** \ **Category:** Factual Questions\ **Created:** [July 20, 2007, 6:31am UTC](https://boards.straightdope.com/t/computer-fan-question/412507 "2007-07-20T06:31:16Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![pkbites](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pkbites/32/204_2.png) [@pkbites](https://boards.straightdope.com/u/pkbites)\ **Post date:** [July 20, 2007, 6:31am UTC](https://boards.straightdope.com/t/computer-fan-question/412507/1 "2007-07-20T06:31:16Z")
As of 2 days ago the fan on my CPU has been running double extra super-duper overtime. I don’t know why. I hven’t installed any new programs or anything. Also it’s not hot in our house. The room the computer is in is actually quite cool. Yesterday I turned it off for the entire day. Turned it back on today and all the fan does is run like crazy. The computer operation itself is fine. Any clues? ---
**Author:** ![IAmNotSpartacus](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@IAmNotSpartacus](https://boards.straightdope.com/u/IAmNotSpartacus)\ **Post date:** [July 20, 2007, 6:41am UTC](https://boards.straightdope.com/t/computer-fan-question/412507/2 "2007-07-20T06:41:04Z")
Your heatsink may be overloaded with dust ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [July 20, 2007, 6:43am UTC](https://boards.straightdope.com/t/computer-fan-question/412507/3 "2007-07-20T06:43:57Z")
Just to satisfy my curiosity, could you explain how you know the CPU fan is running overtime? I’m not much of a computer techie, but IME, the CPU cooling fan isn’t exactly the noisiest thing in your computer. Please keep in mind that my experience is pretty much limited to desktop PC’s with various iterations of the Pentium. Anyway, if your CPU fan is turned on and off as dictated by an RTD-type component, you may wish to consider the possibility the this has opened (practical effect: the temperature control circuitry never “tells” the fan control switch that the CPU is cool enough to safely turn off the fan). ETA: Or what **IAmNotSpartacus** said (practical effect: the CPU actually never _gets_ cool enough to safely turn off the fan). ---
**Author:** ![Archeonomist](https://avatars.discourse-cdn.com/v4/letter/a/7cd45c/32.png) [@Archeonomist](https://boards.straightdope.com/u/Archeonomist)\ **Post date:** [July 20, 2007, 7:01am UTC](https://boards.straightdope.com/t/computer-fan-question/412507/4 "2007-07-20T07:01:59Z")
Well, at least in my PC the CPU fan was absolutely the noisiest thing in there. Which is why I replaced it with a bigger, fixed speed fan. I have a Pentium IV, which is known to run quite hot. Doing something that would stress the processor, like playing games, would make the temperature control circuit crank the fan speed up to max creating lots of noise. Anyway, there are lots of other fans in there as well. I’d suggest you start by installing a program that can monitor the various temperatures and fan speeds inside your PC (Sisoft Sandra for instance) - to see where the problem actually is. If it is the CPU fan, it could be that your heatsink has loosened a bit, and is not leading heat away properly. You could try to remove the fan/heatsink unit and apply more thermal paste to the chip and then reinstall it. ---
**Author:** ![Cowboy8467](https://avatars.discourse-cdn.com/v4/letter/c/b5e925/32.png) [@Cowboy8467](https://boards.straightdope.com/u/Cowboy8467)\ **Post date:** [July 20, 2007, 1:27pm UTC](https://boards.straightdope.com/t/computer-fan-question/412507/5 "2007-07-20T13:27:44Z")
This happened to me with my computer about a year ago. Whenever I would run certain high strain programs the fan would sound like a freaking airplane taking off. Finally I decided to take off the cover and see what was going on inside and lo and behold the entire inside of my computer was blanketed with dust. I was not very good about keeping up with it :smack: . Anyway after blasting it with some compressed air that fixed it right up. ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [July 20, 2007, 5:09pm UTC](https://boards.straightdope.com/t/computer-fan-question/412507/6 "2007-07-20T17:09:04Z")
[QUOTE=Cowboy8467] This happened to me with my computer about a year ago. Whenever I would run certain high strain programs the fan would sound like a freaking airplane taking off. Finally I decided to take off the cover and see what was going on inside and lo and behold the entire inside of my computer was blanketed with dust. I was not very good about keeping up with it :smack: . Anyway after blasting it with some compressed air that fixed it right up. [/QUOTE] A regular cleaning of any PC (desktop or laptop) is essential, but many people don’t do it. Many times, just the air intake/exhaust holes are gummed up with dust, and can cause overheating problems. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 20, 2007, 7:05pm UTC](https://boards.straightdope.com/t/computer-fan-question/412507/7 "2007-07-20T19:05:29Z")
Slight hijack. Does anyone know why computer dust always seems to be a bit greasy? ---
**Author:** ![fishbicycle](https://avatars.discourse-cdn.com/v4/letter/f/aeb1de/32.png) [@fishbicycle](https://boards.straightdope.com/u/fishbicycle)\ **Post date:** [July 20, 2007, 7:25pm UTC](https://boards.straightdope.com/t/computer-fan-question/412507/8 "2007-07-20T19:25:11Z")
I had the same thing happen recently. It got so that after hitting “reboot”, the computer would get as far as the Windows splash screen and shut down. After leaving it off for several hours, then it would boot up again. I looked at the BIOS and it said the core temperature was 92 degrees C, which is 22 degrees more than the thermal shutdown temperature, so BIOS wasn’t allowing it to operate that hot. I looked at the heat sink, and it was caked with dust. I removed the fan and the heat sink, blew out all the dust, hooked it back up and it worked as normal. By the next day, the BIOS said the core temperature was now 40 degrees C. A huge difference. This may be your problem.