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

================== undervolt |travis|

.. |travis| image:: https://travis-ci.org/georgewhewell/undervolt.svg :target: https://travis-ci.org/georgewhewell/undervolt :alt: Build Status

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 <https://github.com/mihic/linux-intel-undervolt>_.

Installing

From PyPi::

$ pip install undervolt

From source::

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

Examples

Read current offsets::

$ undervolt --read
temperature target: -25 (75C)
core: -110.35 mV
gpu: -49.8 mV
cache: -110.35 mV
uncore: -59.57 mV
analogio: -59.57 mV
powerlimit: 35.0W (short: 1.0s - enabled) / 35.0W (long: 1.0s - enabled)

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

Set powerlimit 1 to 35W, 10s:

$ undervolt -p1 35 10

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

.. code-block::

$ undervolt -h
usage: undervolt.py [-h] [--version] [-v] [-f] [-r] [-t TEMP]
                    [--temp-bat TEMP_BAT] [--throttlestop THROTTLESTOP]
                    [--tsindex TSINDEX] [-p1 POWER_LIMIT TIME_WINDOW]
                    [-p2 POWER_LIMIT TIME_WINDOW] [--lock-power-limit]
                    [--core CORE] [--gpu GPU] [--cache CACHE]
                    [--uncore UNCORE] [--analogio ANALOGIO]

optional arguments:
  -h, --help            show this help message and exit
  --version             show program's version number 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 on AC (and battery power if
                        --temp-bat is not used)
  --temp-bat TEMP_BAT   set temperature target on battery power
  --throttlestop THROTTLESTOP
                        extract values from ThrottleStop
  --tsindex TSINDEX     ThrottleStop profile index
  -p1 POWER_LIMIT TIME_WINDOW, --power-limit-long POWER_LIMIT TIME_WINDOW
                        P1 Power Limit (W) and Time Window (s)
  -p2 POWER_LIMIT TIME_WINDOW, --power-limit-short POWER_LIMIT TIME_WINDOW
                        P2 Power Limit (W) and Time Window (s)
  --lock-power-limit    Locks the set power limit. Once they are locked, they
                        can not be modified until next RESET (e.g., Reboot).
  --core CORE           offset (mV)
  --gpu GPU             offset (mV)
  --cache CACHE         offset (mV)
  --uncore UNCORE       offset (mV)
  --analogio ANALOGIO   offset (mV)

Running automatically on boot (systemd)

First, create a unit file /etc/systemd/system/undervolt.service with following contents, replacing the arguments with your own offsets::

[Unit] Description=undervolt After=suspend.target After=hibernate.target After=hybrid-sleep.target

[Service] Type=oneshot

If you have installed undervolt globally (via sudo pip install):

ExecStart=/usr/local/bin/undervolt -v --core -150 --cache -150 --gpu -100

If you want to run from source:

ExecStart=/path/to/undervolt.py -v --core -150 --cache -150 --gpu -100

[Install] WantedBy=multi-user.target WantedBy=suspend.target WantedBy=hibernate.target WantedBy=hybrid-sleep.target

Check that your script works::

$ systemctl start undervolt

Now you may enable undervolt service::

$ systemctl enable undervolt

Or, if you have issue with settings persistence, create a timer /etc/systemd/system/undervolt.timer to trigger the task periodically: ::

[Unit] Description=Apply undervolt settings

[Timer] Unit=undervolt.service

Wait 2 minutes after boot before first applying

OnBootSec=2min

Run every 30 seconds

OnUnitActiveSec=30

[Install] WantedBy=multi-user.target

Now enable and start the timer::

$ systemctl enable undervolt.timer $ systemctl start undervolt.timer

By including the OnBootSec command, settings will not be immediately applied. If you have set overly-aggressive offsets, you will have a short period to disable the timer before it crashes your system::

$ systemctl stop undervolt.timer

Now you can edit your undervolt.service before re-starting the timer.

Running automatically on boot (runit)

First, create a directory for the service::

$ sudo mkdir -p /etc/sv/undervolt

Then create a file named "run" in that directory and edit it to contain these contents::

#!/bin/sh undervolt --core -85 --uncore -85 --analogio -85 --cache -85 --gpu -85 sleep 60

Replace the offsets with your own. Then mark the file as executable::

$ sudo chmod a+x /etc/sv/undervolt/run

Then enable the service::

$ sudo ln -s /etc/sv/undervolt /var/services/

Hardware support

Undervolting should work on any CPU later than Haswell.

================================== ========= ========== System CPU Working? ================================== ========= ========== Acer Aspire 7 (A715-71G) i5-7300HQ Yes Acer Aspire E 15 (E5-575G) i5-7200U Yes Acer Nitro 5 i5-7300HQ Yes Acer Nitro 5 (An515-52) i5-8300H Yes Acer Swift 7 (SF714) i5-8200Y Yes Asus FX504GE i7-8750H Yes Asus GL703GE i7-8750H Yes Dell G5 i7-8750H Yes Dell G5 5590 i7-9750H Yes Dell Inspiron 7560 i7-7500U Yes Dell Latitude 3301 i5-8265U Yes Dell Latitude 5400 i7-8665U Yes Dell Latitude 5480 i5-6300U Yes Dell Latitude 7390 i7-8650U Yes Dell Precision 5530 i9-8950HK Yes Dell Precision 7530 i9-8950HK Yes Dell Precision 7730 E-2176M Yes Dell Precision 7740 E-2286M Yes Dell Precision M3800 i7-4712HQ Yes Dell XPS 13 9343 i5-5200U Yes Dell XPS 13 9350 i7-6560U Yes Dell XPS 13 9360 i7-7560U Yes Dell XPS 15 7590 i7-9750H Yes Dell XPS 15 7590 i9-9980HK Yes Dell XPS 15 9530 i7-4712HQ Yes Dell XPS 15 9550 i7-6700HQ Yes Dell XPS 15 9560 i7-7700HQ Yes Dell XPS 15 9570 i9-8950HK Yes Dell XPS 15 9575 i7-8705G Yes HP Omen 17-an061ur i7-7700HQ Yes HP Spectre X360 i7-8809G Yes HP Zbook Studio G5 i7-8750H Yes Lenovo AIO Y910 27ISH i7-6700 Yes Lenovo IdeaCentre Q190 1017U No Lenovo Thinkpad T430 i7-3610QM No Lenovo Thinkpad T440p i5-4300M Yes Lenovo Thinkpad T470p i7-7700HQ Yes Lenovo Thinkpad T470p i7-7820HQ Yes Lenovo Thinkpad X1 Carbon i7-6600U Yes Lenovo Thinkpad X1 Extreme i7-8750H Yes Lenovo Thinkpad X1 Extreme Gen 2 i7-9750H Yes Lenovo Thinkpad x250 i7-5600U Yes Lenovo X1 Gen 5 i7-7500U Yes Lenovo X1 Yoga Gen 2 i7-7600U Yes Lenovo Yoga 920 i7-8550U Yes MSI GP73 Leopard 8RF i7-8750H Yes MacBook Air Late 2015 i5-5250U Yes MacBook Air Mid 2013 i5-4250U Yes Toshiba Chromebook 2 N2840 No ================================== ========= ==========

Troubleshooting

• Core or Cache offsets have no effect. It is not possible to set different offsets for CPU Core and Cache. The CPU will take the smaller of the two offsets, and apply that to both CPU and Cache. A warning message will be displayed if you attempt to set different offsets.

• OSError: [Errno 1] Operation not permitted First try running with sudo. If the error persists, your system is probably booted in Secure Boot mode. In this case, the Linux kernel will prevent userspace programs (even as root) from writing to the CPU's model-specific registers. Disable UEFI Secure Boot in your system's BIOS and the error should go away.

• Undervolt has no effect - Your device BIOS might be blocking it. Check the wiki (https://github.com/georgewhewell/undervolt/wiki) to find notes for your hardware

GUI

There is also a small gui written in Java avaiable here: https://github.com/zmalrobot/JavaLinuxUndervolt

It will allow you to set each value core, gpu, cache, uncore, analogio (temperature target isn't implemented yet),save a profile, load a profile and reset the value.

Credit

This project is a 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.