Why?

This is useful for those who want to avoid relying on graphical tools like CoreCtrl and prefer an automatic configuration from boot.

Requirements

Hardware

• AMD: GCN or newer GPU (driver amdgpu). Any model released since 2012.
• Intel: Gen6 or newer GPU (driver i915). Any model released since 2012.

System

• Linux with udev support.
• Root access.

Basic Configuration

Performance Levels

AMD

Edit or create the file /etc/udev/rules.d/amdgpu.rules with the following content:

ACTION=="add", SUBSYSTEM=="drm", DRIVERS=="amdgpu", ATTR{device/power_dpm_force_performance_level}="low"

Possible values for power_dpm_force_performance_level:

• auto : GPU adjusts dynamically (default value).
• low : minimum power consumption.
• high : maximum performance.
• manual : user defines specific frequencies.

Advanced Configuration

Granular Frequency Control

pp_* Files

In /sys/class/drm/cardX/device/ you will find parameters to adjust SCLK, MCLK, and power profiles.

Key files:

• pp_dpm_sclk : core frequencies.
• pp_dpm_mclk : memory frequencies.
• pp_power_profile_mode : predefined profiles.
• pp_od_clk_voltage : manual overclock/undervolt.
• pp_od_support : indicates if OverDrive is supported.

Example udev rule:

ACTION=="add", SUBSYSTEM=="drm", DRIVERS=="amdgpu", \
ATTR{device/power_dpm_force_performance_level}="manual", \
ATTR{device/pp_dpm_sclk}="7", ATTR{device/pp_dpm_mclk}="2"

Notes

• The numbers (7, 2, etc.) are DPM states visible with:

  cat /sys/class/drm/card0/device/pp_dpm_sclk
  

• Use manual so frequencies remain fixed.

Intel

gt_*_freq_mhz Files

On Intel, in /sys/class/drm/card0/, you can set minimum, maximum, and boost frequencies (the latter on newer GPUs).

Example udev rule in /etc/udev/rules.d/i915.rules:

ACTION=="add", SUBSYSTEM=="drm", DRIVERS=="i915", \
ATTR{gt_min_freq_mhz}="300", ATTR{gt_max_freq_mhz}="1100", ATTR{gt_boost_freq_mhz}="1100"

Notes:

• Values are in MHz and depend on the model.
• Check current frequencies:

cat /sys/class/drm/card0/gt_*_freq_mhz

Apply Changes Without Rebooting

After modifying or creating rules, run the following commands:

sudo udevadm control --reload-rules

sudo udevadm trigger

Important Considerations

• Setting high frequencies increases power consumption and temperature.
• On laptops, it can drastically reduce battery life.
• Some configurations require special parameters when loading amdgpu or i915.
• If instability occurs, it is recommended to revert to default values (auto).