Maximus VIII Hero PWM fan control not working

[Odaik]

Hello

I am using an Asus Maximus VIII Hero with a 6700K in my new build. The CPU is cooled by a CM 212X air cooler, which comes with a PWM controlled fan.

At first, the fan control on the board worked great (Q-fan PWM mode). However, after about a day or so of use after flashing my BIOS from 1202 to 1504, I noticed the fan has started running at full speed,

I went into the BIOS and no matter what settings I tried for the fan curve, it would not slow down. This was happening under both "auto" and "PWM" control modes. I then tried "DC mode" and it immediately throttled the fan speed back, so it just seems the PWM function is what is faulty here.

I have tried flashing my BIOS back to the previous release (14xx), and also hitting the "CLRCMOS" button on my board and reentering all my settings manually. However, this has made no difference to the situation and DC mode is still all that will allow me to control the speed of my fan.

Any ideas what could be wrong here?

Thanks

[Code_Frenzy]

As a quick test and a way to narrow down the cause of the fault, can you control the fan speed using PWM whilst in the BIOS?

[Odaik]

Code_Frenzy wrote:
As a quick test and a way to narrow down the cause of the fault, can you control the fan speed using PWM whilst in the BIOS?

Sorry, the above details were all describing the behaviour in the UEFI. I don't actually have the AI suite software installed so any changes I make are in the UEFI BIOS.

Chino, I'll test that now and get back to you.

Thanks

[Chino]

Try reconnecting your fan cable. If that doesn't work, test your fan on another fan header.

[Odaik]

OK, tried as suggested. On one of the Chassis Fan headers, the CPU cooler fan behaves in exactly the same way. If I set DC mode, the header controls the fan just fine. If I set it to PWM or auto, the fan runs full speed.

Reconnecting the fan cable didn't make a difference unfortunately.

[hiong]

Odaik wrote:
OK, tried as suggested. On one of the Chassis Fan headers, the CPU cooler fan behaves in exactly the same way. If I set DC mode, the header controls the fan just fine. If I set it to PWM or auto, the fan runs full speed.

Reconnecting the fan cable didn't make a difference unfortunately.

then it's likely a fault with the fan itself. do you have another PWM fan on hand to conclusively test the fan headers?

[Menthol]

I would also suspect the fan, you could always flash back to the older bios if you had no issues before

[Odaik]

Just thought I'd update this thread.

I tried another PWM fan and it worked fine under PWM control so it does indeed look to be a faulty PWM circuit on the fan. Thanks guys!