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?
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.
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.
Sorry, my bad. Pin 3 in BOLT's schematics is tacho input: https://www.udoo.org/docs-bolt/img/bolt_fan_circuit.jpg (You'll have to make sure the fan used is providing techo signal on its pin 3.)
It is the default fan, just wondering other peoples readings on this matter before I try to tinker further with it.
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.
