CPU fan speed won't change

[tiny voices]

Alright I have a problem.

My CPU fan will not increase speed. I have it set to dynamic speed control in the BIOS. It used to properly speed up with CPU temp and slow back down. Now it just sits at 512rpm.

The weird part is that multiple programs confirm that the motherboard is telling the fan to speed up under load (increasing fan speed %), but nothing. The fan does not speed up.

I have flashed the BIOS already. Didn't help

I have tried 3 different PWM fans. All the same deal.

I recently changed between boards without reinstalling Windows. Both MSI z77 boards and I do not know if this happened after the swap. I believe that it only happened recently and was working since the swap.

Any ideas?

 

[JackNaylorPE]

Well all bets are off without a windows reinstall. Your MoBo should have come equipped with a fan control utility on the CD which is much better than BIOS control

What specific MoBo ?

What Fan headers being used ?

What fans (cooler / case / both ) ?

 

[tiny voices]

I have used the motherboard company provided program to try to change the fan speed. I can change it all day, but the fan itself does not actually change speed.

I have used 1 Noctua, 1 Corsair, and 1 Enermax fan. All on the CPU_FAN header.

Board is an MSI Z77ma-G45. I have previously used this board and the fan control has functioned properly.

 

[ex_bubblehead]

If you've tried multiple PWM fans on the same header and had the same problem with all of them then it's possible that whatever drives that header may have failed.

 

[tiny voices]

I thought so, but when you boot the PC the fan spins up to max speed, then down to where it just sits. I know the board will power the header properly.

Also, Even if I set it to run at 100% in the BIOS, and then reboot the PC and re-enter the BIOS, it still just spins at the same slow speed even though the BIOS says it should be at 100%

 

[ex_bubblehead]

That behavior (spin to max, slow down to min on init) may be built into the controller, and the failure is on the input side, where it no longer responds to outside control signals.

 

[tiny voices]

That could be it. I might just try to pick up a cheap z77 board and swap this one out. It isn't a great board to begin with.

 

[Bossyfins]

Update BIOS?

 

[tiny voices]

If you read the first post, you would see that has already been covered.

 

[Bossyfins]

My bad. I doubt a windows reinstall would help. Mobo Drivers? I didnt see anything about motherboard drivers...

 

[Someone Somewhere]

Mobo drivers shouldn't matter; the behaviour is occurring without any OS booted.

Do you know when it started occurring?

 

[Turb0Yoda]

hmm.. Either Windows acting up or the mobo going to die... My solution to test windows, load up a Linux Live USB and try changing stuff from there... Although, I 99% of the time advocate Linux in almost any situation... The fact that you said that it spins up to full on boot makes me doubt it's windows as BIOS doesn't question the HDD for a boot during POST.. most likely motherboard

 

[tiny voices]

I honestly think it started happening today after booting the PC after it sat for like 5 days while I was away.

 

[Someone Somewhere]

Sounds kind of like corrosion somewhere.

That board appears to have 4-pin system fan headers. Do they work correctly?

If you can't find the fault, it's possible that you could set it to ignore the lack of a CPU fan, and use one of the system headers, set to vary based on CPU temp.

 

[tiny voices]

Yes, the SYS_FAN headers all work perfectly fine. That is definitely an option, but I really want to get this sorted properly.

 

[tiny voices]

Connected the CPU fan to the second SYS_FAN header. Works perfectly fine. Idles at 50% and then speeds up with temp. Don;t know why the CPU fan header is toast, but I guess it is.

 

[Tradesman1]

Sounds like it, don't see it too often, any power surges recently

 

[tiny voices]

No nothing like that. Honestly it is a pretty cheap board. (about the worst z77 board). It is also quite old.

 

[Tradesman1]

If changing the mobo, the Rock's Z77 Extreme 4 is a great one and reasonable - I ran a 3570K on mine at 4.7 and carried 32GB of 2400/10 sticks, so it will take whatever you throw at it

 

[tiny voices]

Those are great boards. If I did replace this, I would probably just take whatever I could get cheap to be honest. I have an Antec HCG-750 I'm trying to straight trade for a board over on reddit. I'm not super hell-bent on swapping boards, now that I have this fix though.

 

[Tradesman1]

Hope all goes well 😉

 

[Reynod]

I had a similar problem and put an aftermarket Gigabyte fan speed controller on the box with a variable resistor on a volume knob on the front ... it goes to the fan on the watercooler radiator. When son no 4 games he turns the knob up ... when listening to music he turns it down. I had a similar problem with two different boards over the years. I realise this doesn't help you in the slightest ... my bad.

 

[tiny voices]

Thanks! Makes me feel like this is less of an uncommon thing.