My CPU fan runs to fast

gw186

Golden Member
Sep 7, 2004
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With the case closed the cpu is at 32c and the fan runs at 6000rpm's. It's high piched and starts to sound funny after running that fast for awile. With the side off and full load, temps go up to 40c and the fan never goes above 4800rpm which is fine noise wise.

This is a Sempron 3100 with stock fan I just picked up.

The case has one spot for a fan in front. I have a fan there running around 1600rpm. Could there not be enough air inside, causing the fan to speed up? Does not seem to be heat related. It's an old case so I went and drilled a bunch of holes above the cpu on the side panel. But that did not seem to do anything.
 

rs1089

Member
Oct 6, 2005
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do u have any exhaust fans other than the ones in the power supply? Intake fans do not have as substantial of an effect on cooling than exhaust fans. instead of drilling just a few holes (im assuming it isnt one big hole) drill one big hole and make a duct that leads from the outside of the case to the cpu fan. I still think that u might have an airflow probem.. But i dont think its that u dunt have enough intake; i think its exhaust like i said before. The cpu doesnt seem to hv a heating problem to you but it actually might. If there isnt anything thats really obstructing the flow of the fan, then the cpu is overheating, causing the fan to spin rapidly to keep the cpu at a cooler speed. Reply back with how ur caseflow is set up.
 

gw186

Golden Member
Sep 7, 2004
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The case only has one fan in the lower front for intake. There are no other spots for fans. Besides the holes on the side that I put there there are also 3 rows in the back going from top to bottom. My psu has one fan on the back blowing out.

I am fairly positive it is not from heat. I have cool n quiet inabled(does same thing when off) and at idle it never goes over 32c but the fan spins up to 6000. Two seconds after putting the side on it speeds up. With the side off I ran Prime95 for 30 minutes and got up to 40c and the fan never went over 5000.
 

rs1089

Member
Oct 6, 2005
94
0
61
if there are no rear exhaust fans, then the hot air isnt being expelled quickly enough. see, if the hot air from ur cpu was removed quickly from a fan next to it (rear and not power supply), then the cpu fan wouldnt have to spin rapidly to cool itself off. 2 seconds seems a bit too quick for heating to be an issue. however, u only really have air blowing in, so excluding the power supply, which has hardly enough exhaust power, where else could the air being expelled from the cpu be going?
 

Hacp

Lifer
Jun 8, 2005
13,923
2
81
Originally posted by: Hyperlite
Speedfan


Sometimes, the fan speed control is not done by the mobo but by the fan itself. There are some hs/fans with fan temperature sensors that frankly suck. If that is the case, then I would suggest getting rid of the fan, or giving it away and buying a new one :).