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CPU fan always below 900rpm problem

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Last response: in Systems
October 11, 2011 6:08:45 AM

I just put together a budget build htpc/gaming machine.
What has me stumped, is that the cpu fanis stuck at just below 900rpm.
Fast enough for idle, or barely using the computer, but slower/hotter than what I want for regular use.
When I run stability tester, the cpu comes up to 80 degrees c. Way too hot. All the while, the cpu fan speed stays
at just under 900rpm (at 100% cpu usage)
The computer does stay stable throughout the test, which is nice.
Poking around the bios didn't seem to help.
Googling hasn't turned up anything.
The motherboard is asus m4a785-m (4 pin cpu fan connection, and I'm using a new 4 pin cpu fan)
the cpu: athlon II x3 445 (Unlocked to phenom II x4 b45 no l3 cache)
No overclocking.
ram: ddr2 pc2 6400 2x2gb for 4gb total
PSU: antec earthwatts ea650 green active pfc continuous power

More about : cpu fan 900rpm problem

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October 11, 2011 7:19:51 AM

See what the difference is when you toggle the QFan functionality in the bios. Or if it is even on.
It should be under HW monitor.
October 11, 2011 6:33:56 PM

Nothing changes with qfan on or off. Nothing changes with cool n quiet on or off.
I ended up cutting the 4th wire, just to see the results.
The fan now spins at just over 3,000rpm all the time.
It's still pretty quiet, and the cpu stays below 51 degrees c even with constant 100% cpu usage, so
this situation is much better. However, I would like things to work properly, i.e. the fan speed is adjusted dynamically
as needed. I'm guessing that something is wrong with software/firmware at this point.
Reason being, is that the 4th cpu fan pin on the motherboard obviously does something,
since the fan spins slow, with the wire connected, as compared to fast, with it disconnected.
I can only think to reconnect the wire at this point, and try more bios messing.
I'm stumped