===== 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 [[https://noctua.at/en/products/fan/nf-a9x14-pwm|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)