Intel CPU undervolting tool
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README.md

intel-undervolt

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.

Disclaimer

This tool may damage your hardware since it uses reverse engineered methods of MSR usage. Use it on your own risk.

Building and Installing

Run make && make install to build and install intel-undervolt to your system. Run systemctl daemon-reload to reload unit files.

Configuration

You can configure parameters in /etc/intel-undervolt.conf file.

Voltage Planes

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.

Power Limits

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.

Temperature Limit

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.

Applying Configuration

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.

Daemon Mode

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.