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FANs

CPU FAN

CPU FAN maintains its lowest ~632 rpm even if PWM is set to 0. So it is not possible to stop CPU FAN. Max noticed RPM: 4300

Bottom FAN

Very loud bottom fan, 2 pin only, connected to 4pin connector on MB.

  • Everflow Model: R1292215BL
  • 92 x 92 x 16 [mm]
  • 12V / 0.20A
  • Replacement Noctua NF-A9x14 PWM
    • 12V / 1.32W / 0.11A
    • 92 x 92 x 14 [mm]
    • 19,9 dBa
    • 50.5 CFM
    • 2200 rpm

PWM control is not working. BIOS/MB design is broken ? Workaround is to use CPU FAN PWM to control also bottom FAN.

PWM % CPU rpm Noctua rpm
0 632 0
10 635 0
13 635 stop if started
14 635 cannot start but keep running if started
15 635 cannot start but keep running if started
20 637 cannot start but keep running if started
24 632 starts
30 790
100 4300

AMD Ryzen 7 5825U max temp is 95

Default BIOS for FANs PWM:

  • CPU Fan: Enabled
    • Fan Off(0x68) 30
    • Fan Start(0x69) 35
    • TFull Speed(0x6A) 92
    • Start PWM(0x6B) 40
    • Automatic Mode Control (0x6C) 2
    • Delta Temperature(0x6D) 1
  • System Fan & System Fan 2
    • Fan Off(0x70) 20
    • Fan Start(0x71) 25
    • TFull Speed(0x72) 80
    • Start PWM(0x73) 130
    • Automatic Mode Control (0x74) 4
    • Delta Temperature(0x75) 1

Description:

  • Fan OFF: At this temperature the fan remains off.
  • Fan Start: At this temperature the fan starts to rotate.
  • Full Speed: Not related to PWM. Over this temperature the fan will spin at full speed.
  • Start PWM: This is the percentage of speed at which you want your fan to start spinning when it reaches the temperature indicated in “Fan Start”.
  • Automatic Mode Control: It is PWM slope on 1/8th steps. Setting of 8 in BIOS gives value of 64 in ITE8613e chip register (and also linux sysfs). Max in linux sysfs is 127.
  • Delta temperature: default is 2

How to setup CPU fan. To keep fans quiet and not rotating when possible:

  • Full speed = 89. To protect CPU. Max CPU working temp is 95. Consider that spin-up of CPU FAN takes time. Mine is 89 so if CPU reach 90 it goes full speed.
  • Start PWM = to 25 (percent). This is because 2nd chasis FAN connected to CPU fan start rotating from this value.
  • Fan OFF = 50
  • Fan Start = 60
  • Automatic Mode Control = 4 (raw value 32)