BIOS fan speed measurement

Discussion in 'UDOO BOLT' started by NickGR, Apr 29, 2021.

  1. NickGR

    NickGR UDOOer

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    Hello, I checked my fan speeds in BIOS and at 35% it reports ~6000RPM, and when it hits 100% it reports ~3500RPM, is this some sort of error or cabling problem, did anyone else notice this?
     
  2. ccs_hello

    ccs_hello UDOOer

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    Bolt's CPU fan is a 3-pin type PWM fan which has no tachometer feedback input mechanism.
    Thus whatever the fan speed's readback is not real.
     
  3. NickGR

    NickGR UDOOer

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    The Bolt is not using the signal/tachometer pin at all? Though the "Fan Settings" page mentions about it using the tachometer signal, even the BIOS has the option "Enhanced 3 wire RPM measurement", but if you confirm this is the case then everything is normal. Thank you.
     
  4. ccs_hello

    ccs_hello UDOOer

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  5. NickGR

    NickGR UDOOer

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    It is the default fan, just wondering other peoples readings on this matter before I try to tinker further with it.
     
  6. NickGR

    NickGR UDOOer

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    It seems for the three wire fans, when you PWM, the tachometer gets garbled signals, which is why the "Enhanced 3 wire RPM measurement" exists in the BIOS. Thankfully the Udoo staff helped me understand this and I learned something new.
     

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