MSI B450 Tomahawk PWM fan control broke?

Nexus18 · 5 Jul 2020 at 11:45

Hi all,

After putting the newest bios on, I noticed that my fans weren't set for PWM so I have enabled smart fan control mode and the PWM mode, however, when using hwinfo, it seems like the fans aren't adjusting their speeds

The sys1fan is DC mode as it's only 3 pin but the sysfan 3 and 4 are akassa apache 120mm PWM fans

PieEater · 5 Jul 2020 at 12:35

You need to put some load on the CPU so the temperatures rise and the fan speeds should pick up - your screenshot shows an average CPU temp of 33.2 which is below the minimum temperature you've set in BIOS (40c), until your CPU gets above 40c the fans won't ramp up.

Nexus18 · 5 Jul 2020 at 15:02

PieEater said:
You need to put some load on the CPU so the temperatures rise and the fan speeds should pick up - your screenshot shows an average CPU temp of 33.2 which is below the minimum temperature you've set in BIOS (40c), until your CPU gets above 40c the fans won't ramp up.

Sorry should have explained it better but are the sys/case fans not running rather high considering the temps are low.

akassa apache should be able to drop to 600rpm iirc.

Also, the cpu fan shouldn't be running at that high of a RPM given it's temp?

PieEater · 5 Jul 2020 at 16:22

Hmm OK - I see your temperature source is system, what happens if you select CPU?

Nexus18 · 5 Jul 2020 at 17:34

With CPU selected instead, still the same :confused:

PieEater · 5 Jul 2020 at 17:57

Does your BIOS have a fan autotuning feature where it goes through and detects the fans charecteristics? Otherwise try setting to DC mode rather than PWM for fan control as this should definately work.

Relentless81 · 5 Jul 2020 at 18:06

Are they 20c out? I had that problem on my MSI carbon b450 but it was fixed in the latest bios update and only effected fans set to CPU

Basically the CPU temp was 20c out so 40c was 60c in reality so it looked like they weren't doing anything in windows, might be worth a check

Nexus18 · 5 Jul 2020 at 18:28

PieEater said:
Does your BIOS have a fan autotuning feature where it goes through and detects the fans charecteristics? Otherwise try setting to DC mode rather than PWM for fan control as this should definately work.

Not too sure abut that tbh.

I'll need to jump back into the BIOS later to have a look. But I think the above photo is the only thing I have with regards to fan controls.

I did try DC too but it also doesn't adjust the fan speeds.

Originally, the smart fan mode was disabled and DC was enabled and things appeared to work as they should in terms of the fans changing RPM, however, I thought PWM would have been better and having the case fans set to work with the system temps.

Relentless81 said:
Are they 20c out? I had that problem on my MSI carbon b450 but it was fixed in the latest bios update and only effected fans set to CPU

Basically the CPU temp was 20c out so 40c was 60c in reality so it looked like they weren't doing anything in windows, might be worth a check

Just had a look at the bios versions, I am one version out of date although no mention of that fix in the log but I'll stick it on anyway just in case.

Nexus18 · 5 Jul 2020 at 19:19

Newest BIOS update done and still the same :/

It's not a massive issue as temps are good and case isn't stupidly loud but still annoying how this doesn't seem to be matching up with the low temps.

C64 · 6 Jul 2020 at 03:53

have you cleared cmos after bios update ?

Nexus18 · 6 Jul 2020 at 10:59

C64 said:
have you cleared cmos after bios update ?

Nope.

Will try that later today, thanks.

VaderDSL · 9 Jul 2020 at 11:25

Not using MSI Dragon centre by any chance?

C64 · 9 Jul 2020 at 18:20

Pwm seems pointless I just use 5v 7v 12v linked to cpu temp

Nexus18 · 9 Jul 2020 at 18:59

VaderDSL said:
Not using MSI Dragon centre by any chance?

It's installed and running in the background but no settings are set, I only use it for changing the LED on my MB

VaderDSL · 9 Jul 2020 at 19:47

Nexus18 said:
It's installed and running in the background but no settings are set, I only use it for changing the LED on my MB

Might be worth uninstalling or at least checking the fan control settings in it? It might be overriding the BIOS settings.

Nexus18 · 9 Jul 2020 at 20:26

Checked there and couldn't see anything enabled/set for the fans, have also removed it too.

ShivP · 10 Jul 2020 at 00:04

Try change to DC mode rather than PWM for the fans. I tried that, then it started behaving correctly with Argus Monitor on my MSI B450 Carbon (similar to the Tomahawk)

Nexus18 · 10 Jul 2020 at 11:04

When I switch to DC for the 2 akassa apache fans, they don't even show in HWinfo but they are running.... and look to be running at very low speeds :/

CPU fan still at mad RPM with DC though....

VortexA1 · 11 Jul 2020 at 01:25

ok . Ill put something in the mix. I use Dragon Centre on my MSI board and set a fan curve on the CPU fan and the Sys fans and it worked, did it shortly after building my pc.

How about trying to change them in Dragon Centre?

PieEater · 11 Jul 2020 at 09:25

VortexA1 said:
How about trying to change them in Dragon Centre?

Worth a try, I would reset CMOS and make sure the fan settings are all set to auto beforehand so there is nothing to override the software.

MSI B450 Tomahawk PWM fan control broke?

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