Can't Set CPU Fan Duty Cycle Below 60%

SC489

SC489

SC489

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Joined
4 Apr 2023
Posts
25
Location
UK
I've just built a new PC using an Asus TUF Gaming Plus WiFi Z790 board and a Noctua NH-D14 cooler. The Noctua cooler has a Noctua NF-P12 PWM fan and a Noctua NF-P14 PWM fan connected via a splitter cable to the CPU fan header. All works fine but in the BIOS I can't set a CPU fan duty cycle below 60% for the fan curve whereas I can for the other fans.

Why is this - perhaps something to do with connecting the fans via a splitter cable?
 
If it's like my CH8DH, the only way to change the minimum allowed value is to run the automatic fan tuning thing (I forget what it's called). This tries (emphasis on "tries") to detect the duty cycle that gives minimum RPM for the currently connected fans, and that then becomes the new minimum allowed duty cycle.

If you've done that and it still doesn't let you set anything lower, then try connecting just one fan and run the fan tuning again. If it works, you can then reconnect the splitter.
 
i can't see any sign of fan tuning utility in the BIOS - what do I look for?

I've now connected the two Noctua fans to separate fan connectors (CPU_FAN & CPU_OPT). I still can't set a fan duty cycle below 60% in manual mode in QFan. I'm unsure whether this is by design or a bug.
 
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