undervolt 0.4.0

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, override your systems temperature target (CPU will throttle when this temperature is reached), and adjust the system’s short and long power budgets (clocks and thus voltages will be altered in order to keep total power usage in these periods under the configured limits).

For more information, read here.

Installing

From PyPi:

$ pip install undervolt

From source:

$ pip install git+https://github.com/georgewhewell/undervolt.git

Note for custom kernel users: the module ‘msr’ (“CONFIG_X86_MSR”) must be enabled in the kernel options (Processor type & features -> Model-specific register support)

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)
turbo: 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

Set Intel Turbo disabled:

$ undervolt –turbo 1

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] [--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
  --turbo               Changes the Intel Turbo feature status (1 is disabled and 0 is enabled)
  -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 Predator (PH315-51)	i7-8750H	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 5577	i7-7700HQ	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
Intel NUC7i3BNK	i3-7100U	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 T480s	i5-8250U	Yes
Lenovo Thinkpad T490	i5-8265U	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 GE60 2QD Apache	i7-4720HQ	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.