My BIOS controls my fan speeds, and I want to keep it that way. I have a machine in my basement where it's normally pretty cool, and as long as the machine isn't under high load the fans don't need to run at all. The BIOS already handles this just fine.
But if my fans aren't running, I have no way to test them to make sure they aren't broken. So I'd like to make a script which will turn on the fans full blast for a few seconds, then use lm-sensors to monitor fan speed, and then I will know that the fans aren't broken.
How can I manually turn on the fans to full speed? I don't want to use fancontrol, because I'm not looking for something that keeps running and keeps controlling fan speed. I just want something "low tech" that will turn them on regardless of temperature.
Another thread said:
If you really want to do it yourself, you can probably find special device files named
pwm2, etc. in
/sys/class/hwmon/*/device/. You can cat them to get the current value or write a number between 0 and 255 to change the fan speed.
That would be perfect, but it doesn't seem to work. Fancontrol says that my CPU fan is
/sys/devices/platform/it87.656/pwm3, but when I set that to 255, it doesn't affect fan speed at all.
Does anyone know how I can manually turn on the fan from a script, regardless of temperature?