View Full Version : CPU fan error

21-06-2013, 09:10 PM
Upon start up I get a cpu fan error. About half my boot ups. My system is under my signature. I have an Antec box with a PSU fan and a rear case fan (came with it) and a Coolermaster HSF.

I reattached the cables. Then the error came again. I saw the rear case fan not spinning but the HSF fan was spinning. The rear case fan is attached to the "power fan" connector, the "chassis fan" is another option on the motherboard and is not being used.

Fans are not blocked by cables. System is over 4yrs old, so not under warranty. Advice?

Speedy Gonzales
21-06-2013, 09:47 PM
Wouldnt worry about it. I get it sometimes. I just press F1 to continue. And its fine

21-06-2013, 10:24 PM
simply means the fan speed is set only slightly above the minimum rpm limit set by your bios, this is because you have just started up so there is no stress on the cpu and because its not going to go at a exact speed it is probably dropping below the minimum rpm very slightly. In other words its nothing to worry about.

22-06-2013, 01:52 AM
If you've only just started getting the error after 4 years of service, I would suspect a hardware fault in the speed sensor of the fan itself or the motherboard.

My advice, for a start connect your chassis fan to your chassis fan header. Power fan header is for monitoring the PSU fan and may not actually supply a voltage. Of course if the chassis fan is usually running then it just points to a problem with the board.

If you're worried the fans might stop, tie them to the 12v rail of the PSU from a hard drive plug or such.

22-06-2013, 12:04 PM
Update / Correction.

Yes - only started seeing this error after 4yrs.

The rear case fan - it's actually connected to the molex connector off the IDE DVD-RW (as in peggy back). So there is not signal to the motherboard. There is also another wire off the rear case fan which is the speed selector.
The HSF -connected on the motherboard "CPU FAN" or something on that line.

The mentioned "power fan" or "chassis fan" - is actually the PSU. This is currently connected to the "power fan".

Why is it saying CPU fan error when the HSF is working :confused: This morning again the rear case fan refused to move and still at this moment about 30min into its session. When I had the case open, if I flick the rear case fan with my finger then it moves ...............

22-06-2013, 12:40 PM
Why is it saying CPU fan error when the HSF is working :confused:

Either the RPM readout from the fan is faulty or the motherboard sensor for detecting the signal is faulty. Or you have a bad connection. Try re-plugging the CPU fan connector a few times.

This morning again the rear case fan refused to move and still at this moment about 30min into its session. When I had the case open, if I flick the rear case fan with my finger then it moves ...............

If it needs a push to start it, the bearing(s) are probably stuffed. Most fans use cheap sleeve bearings that wear out and jam. Cold weather doesn't help the lubricant either

22-06-2013, 12:54 PM
As I am using 4yr old equipment and not overclocking maybe I don't need the rear case fan? Also, re: the HSF. The Core Temp software shows my CPU temp approx each of the 4 cores are ~42 degrees. Now over an hour into an session. Maybe I can overlook this issue then 1 or 2yr get a new system?

22-06-2013, 01:00 PM
A good exhaust fan does make a difference especially if you have no other case fans. Fans are pretty damn cheap and one of the easiest things to install, if the rear fan is stuffed you should probably get a new one, if you intend to run the machine for another year or two.

As long as the CPU fan is actually working, it doesn't matter if the readout doesn't work. Of course a failing speed sensor could indicate future problems. If you get used to the fan speed reporting as zero, and the fan does actually fail, you may not realise. Just have to be careful I guess!

bk T
22-06-2013, 01:03 PM
You maybe able to disable the cpu fan warning in the BIOS setup.

22-06-2013, 08:23 PM
You haven't changed any BIOS settings or reset it recently ? I use a hyper 212 cooler on one of my machines and it's start up RPMs are too low for the default BIOS warnings and gives this error you mention all the time. My BIOS lets me lower the warning RPM threshold and that fixes it but any time I've done a BIOS update or reset the BIOS the warning starts happening again.

22-06-2013, 08:26 PM
Haven't went into the bios in yonks ....

23-06-2013, 09:46 AM
I used to have an issue with a worn fan bearing causing it to be slow to spin up at power-on. The BIOS would flag it as an issue at boot, but by the time I could react the fan was at full speed.

Seemed to be more of an issue in cold weather as well, which seems to mirror your situation nicely.

It eventually became a bigger problem as the fan became noisier and evenually would intermittently fail to spin at all. Mine was the CPU fan, so replacing it ASAP was the only good option.