CPU fan speed changes erratically

[Connoisseur]

hey guys,

My rig (in my profile) has a problem with the cpu fan. The speed and pitch vary greatly every once in a while. I normally have the fan at 3500 rpm but it changes from anywhere between 2500 rpm to 4000rpm erratically. And I don't have any automatic fan control software/hardware installed. I thought it might be a psu problem but when I checked psu voltages were rock solid right around their ideal voltages. The reason I thought it might be psu is that once in a blue moon, the system restarts on its own, even when i'm doing nothing. Anybody have any suggestions what it could be? I hope it's not the psu. Is it a dying fan? Also my temps are at 38/36 C at stock setting and like 47/46 C overclocked so I don't think temp is the problem.

 

[WW2Planes1]

What's the cooler type?

 

[Connoisseur]

oh sorry forgout about that. The HS is a Thermalright ALX-800. The fan is a Thermaltake SmartFan II. I adjust fan speed using the potentiometer that came with the fan.

 

[WW2Planes1]

hrm. I was kinda hoping you'd say a Vantec Aeroflow or something with those TMD fans, since that would be easy... those fans were known to do weird things.

anyway, in this case, I'd guess that the potentiometer is dying. I don't know if you can, but try taking the potentiometer out of the loop, just plug the fan straight into the mobo and see if the problem goes away. If not, then it might be the fan, if the problem does stop, then most likely the potentiometer is getting worn out. (did you adjust the fan speed a lot?).

I dunno for certain, but Ii'd guess the random reboots are because you're overclocking

hope it's something simple like that, better a new fan than a new PSU.

 

[Connoisseur]

no it's not cause of the overclock. does it when i'm at stock too. I can prime for hours on end and no errors with the O/C anyway. it's gotta be something else. thx tho.

 

[JimPhelpsMI]

Hi, If it's a three wire fan and plugged into the Mother Board, it's supposed to change speed. That's how it controls the temperature of the CPU. Jim

 

[Zepper]

Quite a few recent mobos have CPU fan control built in - you don't want to use a manually or thermally-controlled fan on them. If you want to use such a fan, disable the mobo's CPU fan control both in the BIOS setup and in your Hardware Monitor software (as the mobo mfr's monitor software can override the BIOS setting)... My Abit KW7 beeps and boops softly when the CPU fan changes speed.
.bh.

 

[amdguy12389]

There is an option in windows to have the computer restart automaticly when windows crashes, disable it. Next time it crashes you should see a blue screen, write down what it says and get back to us.

 

[amdguy12389]

Also have you added voltage to support your frequency overclock? How many amps are your +12v and +5v lines, you might not have a big enough ps unit.

 

[dhoytw]

Sounds to me as though it's an issue with the PS. I would think it could be that or obviously it could be the cooling unit itself.