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CPU fan not spinning, no post

Last response: in Systems
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November 29, 2007 12:04:45 AM

What would cause a CPU fan to not power up with the system? I quadruple checked the fan's power connection and it is correct. The fan works when plugged into the fan connection on a Gigabyte motherboard (although I can't get it to POST). Two different power supplies have been tried - both brand new. While the system does not POST, the heat sink is getting warm (I power down within 30 seconds to avoid damage).

I tried MSI's tech support and received a cookie cutter response - absolutely no help.

Any ideas?

Motherboard: MSI K9NBPM2-FID
CPU: AMD 64 X2 4600+ (65 watt)

More about : cpu fan spinning post

a b B Homebuilt system
a c 125 à CPUs
November 29, 2007 1:22:14 AM

did you make sure to plug a speaker in? the board will give you an error beep code to help you find the problem.

My guess is
RAM? reseat, try one stick, maybe you need more voltage?
4 pin power connector(make sure its on there right)
Are you running the onboard video?
November 29, 2007 1:35:54 AM

Speakers plugged in but there are no beeps. RAM is tight like a tiger.

Four pin connector powers the CPU too, doesn't it? The CPU is getting power as it is getting warm.

On board video until I can get the system running.

How would on-board video or mis-seated RAM cause the CPU fan not to spin?
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November 29, 2007 1:47:18 AM

Did you try clearing the CMOS?
a b B Homebuilt system
a c 125 à CPUs
November 29, 2007 3:08:39 AM

some boards will still run the cpu without it[the 4 pin, but its mostly old boards], just not stable...hell i run a 24pin board with a 20pin psu without problems..

Some boards do not spin the cpu fan until they post....

If all else fails you may need to rma....

Last thing. If its in the case try to take the board out to make sure there is not any shorts to the case....
November 29, 2007 10:49:49 PM

"Some boards do not spin the cpu fan until they post...."

Thanks for the tip I always thought the CPU fan powered up with the system.

"Try this. It's long and a fair amount of work, but it's better than blindly RMA'ing a major component.

http://www.tomswiki.com/page/Troub [...] +New+Build"


Thanks much for the link. Excellent troubleshooting guide. I'll go through it and report back.
a c 122 B Homebuilt system
a c 172 à CPUs
November 30, 2007 4:24:21 AM

I just happened to have Box #1 lying on its side with the side panel off. The CPU fan - plugged into the motherboard CPU fan connector - starts spinning the moment the PC is powered up.
August 5, 2011 11:32:03 PM

Just a quick aside, and sorry if this is a necro, but our problem with no fan spinning was that the wires of the fan wrapped around the case of the CPU fan, and rubbed against the fan baldes with just enough resistance to keep it from turning.

This page is the top google hit for "fan not spinning", so I figured I'd throw this in here, in case anyone else has such a solution to their problem.
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