Warning! This program is untested (apart from by myself) and it may damage your hardware! Use at your own risk.
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.
From PyPi:
$ pip install undervolt
From source:
$ git clone https://github.com/georgewhewell/undervolt.git
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
$ 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)
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.
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/
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 |
| Asus FX504GE | i7-8750H | Yes |
| Asus GL703GE | i7-8750H | Yes |
| Dell G5 | i7-8750H | Yes |
| Dell Inspiron 7560 | i7-7500U | 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 M3800 | i7-4712HQ | Yes |
| Dell Precision 7530 | i9-8950HK | Yes |
| Dell Precision 7730 | E-2176M | Yes |
| Dell Precision 7740 | E-2286M | Yes |
| Dell XPS 13 9343 | i5-5200U | Yes |
| Dell XPS 13 9360 | i7-7560U | 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 |
| Dell XPS 15 7590 | i9-9980HK | Yes |
| HP Spectre X360 | i7-8809G | Yes |
| HP Zbook Studio G5 | i7-8750H | Yes |
| Lenovo Thinkpad T440p | i5-4300M | Yes |
| Lenovo Thinkpad T470p | i7-7700HQ | Yes |
| Lenovo Thinkpad x250 | i7-5600U | 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 X1 Gen 5 | i7-7500U | Yes |
| Lenovo X1 Yoga Gen 2 | i7-7600U | Yes |
| Lenovo Yoga 920 | i7-8550U | Yes |
| MacBook Air Mid 2013 | i5-4250U | Yes |
| MacBook Air Late 2015 | i5-5250U | Yes |
| MSI GP73 Leopard 8RF | i7-8750H | Yes |
| Lenovo Thinkpad T430 | i7-3610QM | No |
| Toshiba Chromebook 2 | N2840 | No |
- 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 permittedFirst try running withsudo. 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.
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.
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.