intel-undervolt is a tool for undervolting Haswell and newer Intel CPUs using MSR. This tool is based on the content of this article.
This tool also allow to alter power limits and temperature limit using MSR and MCHBAR registers.
This tool may damage your hardware since it uses reverse engineered methods of MSR usage. Use it on your own risk.
Run make && make install to build and install intel-undervolt to your system.
Run systemctl daemon-reload to reload unit files.
You can configure parameters in /etc/intel-undervolt.conf file.
By default it contains all voltage planes like in ThrottleStop utility for Windows.
The following syntax is used in the file: apply ${index} ${display_name} ${undervolt_value}.
For example, you can write apply 2 'CPU Cache' -25.84 in order to undervolt CPU cache by 25.84 mV.
tdp ${short_term} ${long_term} can be used in order to alter short term and long term
power limits. For example, tdp 35 25.
You can also specify a time window for each limit in seconds. For instance, tdp 35/5 25/60 for
5 seconds and 60 seconds respectively.
tjoffset ${temperature_offset} can be used in order to alter temperature limit. This value
is subtracted from max temperature level. For example, tjoffset -20. If max temperature level
is set to 100, the resulting limit will be set to 100 - 20 = 80°C. Note that offsets
higher than 15°C are allowed only on Skylake and newer.
Run intel-undervolt read to read current values and intel-undervolt apply to apply configured
values. You can apply your configuration automatically enabling intel-undervolt.service.
Sometimes power and temperature limits could be reset by EC, BIOS, or something else. This behavior
can be suppressed applying limits periodically. intel-undervolt-loop.service allows you to run
the program and daemon mode which will apply limits with the specified interval. You can change the
interval using interval ${interval_in_milliseconds} configuration paremeter.