Question about correlation of CHA_FAN sockets and pwm control

[fjaoos]

Hello friends,

 

I am wondering how the pwm control units are correlated to the fans that are plugged in. The motherboard in question is an ASUS H97-Plus.

• One 120mm 3Pin fan is connected to CHA_FAN1
• One 120mm 4Pin fan is connected to CHA_FAN2
• No Fan is connected to CPU_FAN (The Noctua NH-D15 runs fine in passive mode)

 

When running pwmconfig I get the following output:

# pwmconfig version 3.6.0
This program will search your sensors for pulse width modulation (pwm)
controls, and test each one to see if it controls a fan on
your motherboard. Note that many motherboards do not have pwm
circuitry installed, even if your sensor chip supports pwm.

We will attempt to briefly stop each fan using the pwm controls.
The program will attempt to restore each fan to full speed
after testing. However, it is ** very important ** that you
physically verify that the fans have been to full speed
after the program has completed.

Found the following devices:
   hwmon0 is acpitz
   hwmon1 is nvme
   hwmon2 is coretemp
   hwmon3 is nct6791

Found the following PWM controls:
   hwmon3/pwm1           current value: 84
   hwmon3/pwm2           current value: 255
hwmon3/pwm2 is currently setup for automatic speed control.
In general, automatic mode is preferred over manual mode, as
it is more efficient and it reacts faster. Are you sure that
you want to setup this output for manual control? (n) yes
   hwmon3/pwm3           current value: 111
   hwmon3/pwm5           current value: 255

Giving the fans some time to reach full speed...
Found the following fan sensors:
   hwmon3/fan1_input     current speed: 1299 RPM
   hwmon3/fan2_input     current speed: 0 ... skipping!
   hwmon3/fan3_input     current speed: 1344 RPM
   hwmon3/fan5_input     current speed: 0 ... skipping!

Warning!!! This program will stop your fans, one at a time,
for approximately 5 seconds each!!!
This may cause your processor temperature to rise!!!
If you do not want to do this hit control-C now!!!
Hit return to continue: 

Testing pwm control hwmon3/pwm1 ...
  hwmon3/fan1_input ... speed was 1299 now 379
    It appears that fan hwmon3/fan1_input
    is controlled by pwm hwmon3/pwm1
Would you like to generate a detailed correlation (y)? y
    PWM 255 FAN 1284
    PWM 240 FAN 1235
    PWM 225 FAN 1218
    PWM 210 FAN 1115
    PWM 195 FAN 1063
    PWM 180 FAN 996
    PWM 165 FAN 909
    PWM 150 FAN 846
    PWM 135 FAN 794
    PWM 120 FAN 714
    PWM 105 FAN 637
    PWM 90 FAN 560
    PWM 75 FAN 459
    PWM 60 FAN 368
    PWM 45 FAN 201
    PWM 30 FAN 0
    Fan Stopped at PWM = 30

  hwmon3/fan3_input ... speed was 1344 now 1317
    no correlation

Testing pwm control hwmon3/pwm3 ...
  hwmon3/fan1_input ... speed was 1299 now 1212
    no correlation
  hwmon3/fan3_input ... speed was 1344 now 0
    It appears that fan hwmon3/fan3_input
    is controlled by pwm hwmon3/pwm3
Would you like to generate a detailed correlation (y)? y
    PWM 255 FAN 1320
    PWM 240 FAN 1260
    PWM 225 FAN 1197
    PWM 210 FAN 1139
    PWM 195 FAN 1073
    PWM 180 FAN 1008
    PWM 165 FAN 949
    PWM 150 FAN 877
    PWM 135 FAN 809
    PWM 120 FAN 734
    PWM 105 FAN 674
    PWM 90 FAN 580
    PWM 75 FAN 0
    Fan Stopped at PWM = 75


Testing pwm control hwmon3/pwm5 ...
  hwmon3/fan1_input ... speed was 1299 now 436
    It appears that fan hwmon3/fan1_input
    is controlled by pwm hwmon3/pwm5
    Fan hwmon3/fan1_input has not returned to speed, please investigate!
  hwmon3/fan3_input ... speed was 1344 now 1319
    no correlation

Testing is complete.
Please verify that all fans have returned to their normal speed.

The fancontrol script can automatically respond to temperature changes
of your system by changing fanspeeds.
Do you want to set up its configuration file now (y)? n

 

Why are there 3 pwm controllers available?