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Problems with CPU Fan stopping

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Hi,
my Hackintosh run troublefree for around one year but now there's a problem with my CPU cooler. Sometimes (not that frequent) it just stops running. Its "rpm" disappears from HWMonitor and that's it. Sometimes the problem occurs even right from the start. Normally, when I hit the power on button the fan spins for half a second and starts getting slow, just before it stops something kicks in and its rpm increase to a normal value. From time to time this very important "kick" is missing.

The problem is, I renewed some kexts approx a month ago to get things like GBit Lan (was still on the old kext from a year ago), one of them was FakeSMC. When I first noticed the CPU rpm to disappear in HWMonitor I thought it was a bug within the program and nothing else. My cooling is pretty good and when there's no heavy usage on the CPU it gets barely warmer than usual. Therefore I can't tell when the problem starts. I even upgraded my UEFI from F8 to F9 for... no reason. I downgraded it yesterday, dunno if that fixed anything.


The question is: what's the problem? Fan? Motherboard? Some software issue? Any ideas? :/
 
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sound's like PSU , if you have spare check with it :)
 
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What cooler/fan are you using on that CPU? Are the temperatures critical when the fan is not working?
 
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It's a Scythe Mugen 2 and if the CPU is just idling the temps remain fine (although slightly above average).
However, I enabled the UEFI CPUFan and CPU temp warning noise.

sound's like PSU , if you have spare check with it :)
The fan is plugged into CPUFAN on the motherboard. If it's a problem with the PSU shouldn't other components driven by the motherboard suffer too?
 
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Ok, the fan on the cooler is PWM controlled. That means, the fan is always getting 12v, but also gets a signal on the 4th pin for the speed. That signal is controlled by the mainboard and depends on the CPU temperature.

PWM fans are always getting a 100% signal after the PC is starting, by that the mainboard is recognizing if a PWM fan is installed or not.
If your fan is shutting down I would guess that the fan is getting a very low PWM signal at which the fan can't operate.

Can you check your cooling setting in the BIOS (pc health section or sth similar)?
At which temperatures the fan is stopping?
 
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Ah okay, thanks.
BIOS settings for controlling the fan (V/PWM) is set to "Auto" and the cooling to "Normal".
I found no "pattern" (regarding temperature or something like that) yet but I'll watch out.
Though I doubt it's due to high temperature. When it happened the last times it was right after the start or during times with roughly 5% load. Occasionally I do (or: did, last time was around 3 months ago) some encoding where the cpu is at 100% for around 12-x hours and there was no problem to date.

If your fan is shutting down I would guess that the fan is getting a very low PWM signal at which the fan can't operate.
I guess there's no way verifying this like changing the PWM signal by hand? :S

So the fans are not controlled by software like SMC? It has to be a hardware problem?
 
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You can ste the Fan control to PWM (not Auto). After that you should be able to select "profiles" like silent, normal, extreme. Maybe you can play with that settings.
 
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A few days ago I replaced the fan attached to the heat-pipe-thing and the problems vanished. It seems like it was some kind of defective contact. :)
 
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