Can I control a chassis fan attached to CPU_OPT header?

[lmacmil2]

I have 3 chassis fans, 2 intakes and 1 exhaust.  All 3 show up on the BIOS main screen.  When I go to the Q-fan control page, only Chassis1 and Chassis2 show up.  The fan attached to the CPU_OPT header is a 140mm PWM fan and is only running about 600rpm.  I would like to increase that speed a little to get better airflow through the chassis.  Is there a way to do that or do I have to switch the PWM fan to the Fan2 header?  When I had a DC fan attached to CPU-OPT, it ran about 1400rpm.  If I say the PWM fan is a DC fan, will that speed it up?

[smithalex]

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@lmacmil2fuse Ocado wrote:

I have 3 chassis fans, 2 intakes and 1 exhaust.  All 3 show up on the BIOS main screen.  When I go to the Q-fan control page, only Chassis1 and Chassis2 show up.  The fan attached to the CPU_OPT header is a 140mm PWM fan and is only running about 600rpm.  I would like to increase that speed a little to get better airflow through the chassis.  Is there a way to do that or do I have to switch the PWM fan to the Fan2 header?  When I had a DC fan attached to CPU-OPT, it ran about 1400rpm.  If I say the PWM fan is a DC fan, will that speed it up?

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To increase the speed of your PWM fan attached to the CPU_OPT header, you might need to adjust the fan settings in BIOS. Switching the fan to the Fan2 header might give you more control, as some headers are optimized for PWM fans. Saying the PWM fan is a DC fan won't speed it up, as PWM and DC fans operate differently. Check your BIOS for fan curve settings or try manually adjusting the fan speed for better airflow.

[lmacmil2]

There is no speed adjustment for the CPU_OPT fan in the BIOS Q-fan section.  It doesn't show up.  I will trying switching the PWM fan to the Fan2 header.

[lmacmil2 · Accepted solution]

I put the PWM fan on the Fan2 header and can control the speed.  I have daisy-chained a DC fan which I believe is now running at full speed or close to it.  That's fine, the temp of my NVME drive is where I want it to be.