Sunday, 2 October 2011

How to manually configure system fan speeds in linux

If someone is interested to manually configure his system’s fans  then he can try (lm-sensors should be installed for following command to run )
sudo pwmconfig

pwm stands for pulse width modulating - it means fan speed is regulated by turning fan’s power supply on and off at fixed frequency.
NOTE- This command can be dangerous and proceed with care. After running above command, ensure that all of your computer’s fans are running.

When above command is run, it shows you the temperature and fan sensors it detects and asks you whether you want to do manual configuration or not. Enter ‘y’ there. 

Then it will ask
Did you see/hear a fan stopping during the above test (n)?  
Enter ‘y’ (may even enter ‘y’ without hearing fan stop but it is risky)

Then if you have package gnuplot installed, it will ask whether you want to make a graph of fan speed. enter ‘y’. Then it will test fan speeds corresponding to different pwm values. Repeat above procedures for all the fans.

When all fan detecting is finished, it will ask  
if you want to set up configuration file. Enter ‘y’ and then enter. Then screen will come as follows :-

Enter one of the fan which was detected . Now here comes the trickiest part. Now when you select the desired fan to configure, it will show you all the temperature sensors and ask with which sensor’s reading you want to synchronise the selected fan’s speed. For this, you should know which fan belong to which cpu component ( can be known by opening up the cpu case and observing which fan’s speed fluctuates when pwmconfig is varying fan speeds ). After you do that, you will have to configure parameters such as when the fan should stop running, when it should run fastest, etc and then when you have defined all the parameters, it will again ask to select a fan output to configure or choose another option ( as in the end of above screenshot ). 

After you have configured all your fans, just save and quit from menu. Now you have configured all your fans manually. 

By -
Sahil Mahajan and Jatin Sindhu

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