THIS SCRIPT MAY PHYSICALLY DAMAGE YOUR SYSTEM. USE ONLY AT YOUR OWN RISK. I AM NOT RESPONSIBLE TO ANY DAMAGE CAUSED BY USING THESE SCRIPTS.
Should work with all i* CPUs that are newer or equal than 6th gen.
Tested for i7 7th gen CPU on XPS 15 9560. It seems to be stable with around -100mV for both CPU and GPU.
The script is based on an tutorial in which the MSR configuration used by the regulators were reverse engineered. There is no official documentation available, so this is all based on guess-work and reverse engineering.
Run ./install.sh as root. This will set up the config file, the systemd scripts and the script itself. It also enables systemd startup. Edit /etc/undervolt.json and fill your values (in negative millivolts).
Please always test your values just by running sudo undervolt -cpu <value> -gpu <value> before writing them to the config file, as if may result in an unbootable system if the voltages are switched to unstable value during boot time.
The script is written in python3. msr kernel module is required for accessing CPU MSR registers.
CPU voltage can be checked with i7z util, by running it as root.