undervolt 0.2.5

Undervolt Intel CPUs under Linux

Warning!

This program is untested (apart from by myself) and it may damage your hardware! Use at your own risk.

undervolt

undervolt is a program for undervolting Intel CPUs under Linux. It works in a similar manner to the Windows program ThrottleStop (i.e, MSR 0x150). You can apply a fixed voltage offset to one of 5 voltage planes, and override your systems temperature target (CPU will throttle when this temperature is reached).

For more information, read here.

Installing

From PyPi:

$ pip install undervolt

From source:

$ git clone https://github.com/georgewhewell/undervolt.git

Examples

Read current offsets:

$ undervolt --read
temperature target: -0 (100C)
core: 0.0 mV
gpu: -19.53 mV
cache: -30.27 mV
uncore: -29.3 mV
analogio: -70.31 mV

Apply -100mV offset to CPU Core and Cache:

$ undervolt --core -100 --cache -100

Apply -75mV offset to GPU, -100mV to all other planes:

$ undervolt --gpu -75 --core -100 --cache -100 --uncore -100 --analogio -100

Set temperature target to 97C:

$ undervolt --temp 97

Generated the command to run to recreate your Throttlestop settings:

$ undervolt --throttlestop ThrottleStop.ini --tsindex 3
undervolt --core -100.5859375
$ undervolt --throttlestop ThrottleStop.ini
undervolt --core -125.0 --gpu -125.0 --cache -125.0

Usage

$ undervolt -h
usage: undervolt.py [-h] [-v] [-f] [-r] [-t TEMP]
                    [--throttlestop THROTTLESTOP] [--tsindex TSINDEX]
                    [--core CORE] [--gpu GPU] [--cache CACHE]
                    [--uncore UNCORE] [--analogio ANALOGIO]
optional arguments:
  -h, --help            show this help message and exit
  -v, --verbose         print debug info
  -f, --force           allow setting positive offsets
  -r, --read            read existing values
  -t TEMP, --temp TEMP  set temperature target
  --throttlestop THROTTLESTOP
                        extract values from ThrottleStop
  --tsindex TSINDEX     ThrottleStop profile index
  --core CORE           offset (mV)
  --gpu GPU             offset (mV)
  --cache CACHE         offset (mV)
  --uncore UNCORE       offset (mV)
  --analogio ANALOGIO   offset (mV)

Hardware support

Undervolting should work on any CPU later then Haswell.

System	CPU	Working?
Lenovo Yoga 920	i7-8550U	Yes
Lenovo X1 Yoga Gen 2	i7-7600U	Yes
Lenovo Thinkpad T470p	i7-7700HQ	Yes
Dell Xps 13 9343	i5-5200U	Yes
Dell Xps 15 9560	i7-7700HQ	Yes
Dell Xps 15 9550	i7-6700HQ	Yes
MacBook Air Mid 2013	i5-4250U	Yes

Credit

This project is trivial wrapper around the work of others from the following resources:

• https://github.com/mihic/linux-intel-undervolt

• http://forum.notebookreview.com/threads/undervolting-e-g-skylake-in-linux.807953

• https://forums.anandtech.com/threads/what-controls-turbo-core-in-xeons.2496647

Many thanks to all who contributed.