How to set persistent power governor at boot time

What is power governor?
Power governor in Linux plays the same role as power plan in Windows.
It's used to control power frequency, heat emmision, battery usage.

First, install cpufrequtils

sudo apt-get install cpufrequtils

Check the list of available governors

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

Using your favorite editor create or edit following file (as superuser)

/etc/default/cpufrequtils

Update or add following line

GOVERNOR="conservative"

Reboot system

sudo reboot

Check enabled governor

sudo cpufreq-info | grep T

Common governors

Performance - highest cpu frequency, short battery, more heat

Powersave - lowest cpu frequency, save battery, less heat

Ondemand - will act as performace during high cpu usage and as powersave otherwise.

Conservative - similar to ondemand, but changes are fluent.

Done.