pwmconfig Man page

PWMCONFIG(8) System Manager’s Manual PWMCONFIG(8)


pwmconfig – tests the PWM outputs of sensors and configures fancontrol



pwmconfig will attempt to stop your fans, one at a time, for approxi‐
mately 5 seconds each. This may cause your processor temperature to
rise. Verify that all fans are running at normal speed after this pro‐
gram has exited. pwmconfig does its best to check that the fans are
spinning when they are supposed to, but due to the diversity of avail‐
able motherboards and fans, it shouldn’t be blindly trusted. Always
verify by yourself.

It is strongly recommended to run pwmconfig at a time when there is no
significant system load, to minimize the risk of overheating.


pwmconfig searches your sensors for pulse width modulation (PWM) con‐
trols, and tests each one to see if it controls a fan on your mother‐
board. Note that many motherboards do not have PWM circuitry installed,
even if your sensor chip supports PWM.

When a connection is established between a PWM control and a fan, pwm‐
config can generate a detailed correlation, to show how a given fan is
responding to various PWM duty cycles.

Lastly, pwmconfig will enter in fancontrol configuration mode (unless
you decide to skip that part.) In this mode, you are invited to enter
several parameters which will determine how the fancontrol daemon regu‐
lates the speed of one or more fans in your system based on temperature
measurements. In particular, you will have the opportunity to establish
mappings between fans and temperature inputs, define the temperature
range over which the speed of the fan should be adjusted dynamically,
the minimum speed at which the fan should spin, etc. See fancontrol(8)
for additional information.


The term “PWM” is used because most fan control systems in computers
are based on pulse width modulation. Some motherboards however use DC
variation instead. So, the term “PWM” should be seen as a generic term
for “fan speed control”, regardless of the actual method used.


fancontrol(8), sensors.

Marius Reiner , Jean Delvare

lm-sensors 3 September 28, 2008 PWMCONFIG(8)

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