Linux – Set Fan Speed by RPM on Thinkpad T420s

acpifanlinuxthinkpad

The only interface I've found for setting the fan speed with the thinkpad-acpi module, is setting pre-defined levels, 0-7. Example:

sudo su -c 'echo "level 2" > /proc/acpi/ibm/fan'

I would like to set the fan speed by RPM and not by pre-defined levels. Level 2 is 2000 RPM, and level 3 is 3500 RPM. I would like my fan to run at about 2500-3000 RPM (at a certain temperature level, of course). Does a RPM based interface exist?

Best Answer

Seems that it's dependent on the hardware's firmware. As the README page says:

Most ThinkPad fans work in "levels" at the firmware interface. Level 0 stops the fan. The higher the level, the higher the fan speed, although adjacent levels often map to the same fan speed. 7 is the highest level, where the fan reaches the maximum recommended speed.

and

On the X31 and X40 (and ONLY on those models), the fan speed can be controlled to a certain degree. Once the fan is running, it can be forced to run faster or slower with the following command:

echo 'speed <speed>' > /proc/acpi/ibm/fan
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