Random fan speed changes

[Ranulf]

Odd issue with my cpu fan, looking for any info on the why...

I had my hyper 212 evos fan start up this morning with random speed ups and downs, while downloading win7 updates (fresh install awhile back on an amd 955 chip). Started normal around 600-800rpm at idle but it was jumping all over from 800-1800+ rpm while updating windows 7 for about an hour. Often it was very quick speed up and back down again, rather loud.

System seems fine now post updates. Its been running Prime95 between 41C and 57C and the fan is quiet at 1300-1500 rpm for almost an hour. Idles at 25C and 700rpm.

 

[BonzaiDuck]

Is this the 2500K system or one of the others?

Which motherboard?

As far as I can tell, the fan-control features in BIOS and software are at parity between AMD and Intel.

I have an ASUS board. In order to get abs-o-lute thermal control of fan speed, I have to tweak the fan-control settings in BIOS. But! If I want to customize fan behavior even more, I have to select "User" or "Custom" for both the CPU and chassis-fan BIOS settings.

Once that's done, the ASUS Windows software allows creation of fan curves in conjunction with the BIOS choices, and I never have to touch the Fan-Xpert software again. But if I change the BIOS from "User" to "Turbo" or "Normal," the software configuration no longer applies.

If you say this happened at the time of a Windows update or upgrade, one could only guess that the fan-control settings set the stage for a threshold where a minor temperature boost caused them to behave as you described.

If all is fine now, just keep an eye on it.

ALSO. Is the CPU fan a PWM fan or a 3-pin unit? PWM fan requires circuitry within the fan to respond to a PWM signal from the mobo.

I don't like to spend money, and I believe the little nickels and dimes defeat our personal money management. But here's a policy I follow. I never -- or very seldom -- bother using the fans that came with a cooler. I think some of the CoolerMaster fans suck like an old Victorian bathtub. Others -- sold separately -- seem to have a following of people who like them.

I'd recommend you look for a fan like the Akasa Viper -- probably a 120x25mm -- or any other PWM fan with a decent reputation. Cougar Vortex is often touted, but I'd rather have stronger CFM specs.

THEN see what happens . . . . Unless, of course, everything remains copacetic with the fan you're using now.

 

[Ranulf]

Hey Bonzai, thanks for the reply.

Its the Phenom II 955 (stock 3.2) on a gigabyte GA-78LMT mobo. I've not touched anything in the bios on fan settings. Its a PWM fan that comes with the 212 evo and the 3 case fans (fractal design) are not hooked into the mobo but the case fan switch. I think I'll just keep an eye on it for now after it seemed normal for an hour on prime95/intel burn test. I have a noctua 120mm cpu fan I could try or a corsair one somewhere if the CM one acts up again.

I'm set to install win10 test on it soon so...could be fun times there.

 

[BonzaiDuck]

Hey Bonzai, thanks for the reply.

Its the Phenom II 955 (stock 3.2) on a gigabyte GA-78LMT mobo. I've not touched anything in the bios on fan settings. Its a PWM fan that comes with the 212 evo and the 3 case fans (fractal design) are not hooked into the mobo but the case fan switch. I think I'll just keep an eye on it for now after it seemed normal for an hour on prime95/intel burn test. I have a noctua 120mm cpu fan I could try or a corsair one somewhere if the CM one acts up again.

I'm set to install win10 test on it soon so...could be fun times there.

Not so much related in any way with your anomaly, but just know there is a general pattern of difficulty and frustration with new OS versions just-released or in Beta: there's often a dearth of hardware drivers that work with the newest OS. I usually wait for the first service pack release before adopting a new version, when I once jumped on every new version as soon as it appeared.

I think we had some survey results here at the forums. Something like 60% of forum members are still using Win 7 (as am I!)

I find that interesting, since most or many forum members seem obsessively eager for everything "latest and greatest."