4-pin noctua fans only working at above 90% pwm

[shirnschall]

Hi, I am trying to get a 120mm noctua nf f12 industrial fan (12V, 4pin pwm) to work as apart cooling fan. I have connected it as described in the documentation and as shown in the image below.

The problem is that the pwm control is not working correctly. The fan turns off at any level below approx. 80 and only turns on at 90 and above.
I have tested two different nf-f12 fans with the same result.

My setup:
I am currently using the duet2 wifi with the duex5 running at 24V with an external 5V supply. I am using RRF 3.4.1 (2022-06-01) and in my config.g I configure the fan using

M950 F2 C"!fan2"  ; fan 2 part cooling fans nf-f12. output is inverted for 4-wire fan
M106 P2 C"Adv-Part-Cooling" S0 F25000    ; set fan 1 name, value, PWM signal inversion and frequency. Thermostatic control is turned off

I have also tried adding a 10k Ohm pullup between the pwm input of the fan and +5V as mentioned here: https://forum.duet3d.com/topic/25179/wiring-configuration-of-standard-4-pin-pwm-fans-on-duet-3-mb6hc
Increasing the B-value as mentioned here https://forum.duet3d.com/topic/25127/configuring-a-pwm-4-wire-fan causes the fan to spinn up briefly before spinning back down again.

[shirnschall]

@shirnschall After trying to get this to work for weeks, I found the error right after posting.

I used the old RRF 2

M106 F25000

to set the pwm frequency when it has changed to

M950 Q25000

in RRF 3.
The fans now work down to around 40% as expected.