amdctl

Set P-State voltages and clock speeds on recent AMD CPUs on Linux.

Disclaimer:

This software can damage your hardware, use at your own risk.

Description:

Tool for changing voltages and clock speeds for AMD processors with control over every power state and CPU core.

Compilation:

You can compile with the program make.

Usage:

Make the binary executable chmod +x amdctl.
Run the program for a list of options, you can type ./amdctl to run it.
./amdctl -x to get a description of the various words used in the program.

Undervolting:

Undervolting is done by increasing the value of the CpuVid field for a specific P-state.
This can be done by invoking 'sudo /path/to/amdctl -pP -vV' in console, where P is the P-state of which the CpuVid you want to change and V is the value you want the CpuVid field to have.
For example, 'sudo /path/to/amdctl -p1 -v25' will change the value of the CpuVid field of P-state #1 to 25.
This applies the undervolt to all cores. You can specify a core by using the -c flag.

Supported CPU Families:

AMD CPU family's 10h(K10), 11h(Turion), 12h(Fusion), 14h (Bobcat), 15h(Bulldozer), 16h(Jaguar), 17h(Zen, Zen+, Zen 2), 19h(Zen 3).
This would be most AMD CPU's between 2007 and 2021.

You can find your CPU family by typing cat /proc/cpuinfo in a terminal, the values there are in decimal.
10h is equivalent to 16, 16h 22 for example. See https://en.wikipedia.org/wiki/List_of_AMD_CPU_microarchitectures for a table with all AMD CPU families.

The program will check if your CPU is supported when run.

Unsupported CPU Families:

AMD CPU family 9h(K9) and earlier.
AMD 13h, I could not find any info on this, so I assume this CPU family does not exist.
AMD 18h(EPYC / Hygon Dhyana), no public documentation available ?
Anything newer than 19h (for now).

Requirements:

• Root access.
• Msr kernel module.

To manually load the msr module: sudo modprobe msr
To automatically load the msr module see the arch wiki.

On Kernel's 5.9 and higher, userspace writes to MSR are restricted, for now (in the future this may become impossible) you can allow writing to MSR from userspace using one of the following methods:

• Using amdctl: Pass the -m option: sudo ./amdctl -m -g
• After the kernel is loaded (runtime): sudo bash -c "echo on > /sys/module/msr/parameters/allow_writes"
• When loading the kernel: Add msr.allow_writes=on to kernel parameters : https://wiki.archlinux.org/title/kernel_parameters

References:

https://developer.amd.com/resources/developer-guides-manuals/ https://wiki.archlinux.org/index.php/K10ctl http://sourceforge.net/projects/k10ctl/ https://web.archive.org/web/20090914081440/http://www.ztex.de/misc/k10ctl.e.html https://01.org/msr-tools https://en.wikipedia.org/wiki/List_of_AMD_CPU_microarchitectures http://users.atw.hu/instlatx64/