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GlouOS Wiki › Under the hood › CoreCtrl GPU tuning

CoreCtrl GPU tuning

GlouOS bundles CoreCtrl, the AMD equivalent of MSI Afterburner, and unlocks its controls at install time. Fan curves, clocks, undervolting and power limits work from the first boot instead of sitting greyed out.

CoreCtrl, the AMD tuning tool

CoreCtrl is the go-to tool for tuning AMD graphics cards on Linux: fan curves, clock control, power limits and per-application GPU profiles, all from a friendly GUI. GlouOS ships it out of the box.

On most distros, though, opening CoreCtrl is a letdown. The amdgpu kernel driver boots with its PowerPlay feature mask locked down: overdrive (manual tuning) is disabled, so CoreCtrl shows sensors and every interesting slider is greyed out. The tool looks broken when it is really just locked.

Unlocked at install, only when it applies

Unlocking those controls requires a kernel boot parameter:

amdgpu.ppfeaturemask=0xffffffff

It enables every PowerPlay feature bit, including the one that turns on manual fan, clock and voltage control. During installation, the same hardware-detection step that picks your graphics driver stack checks which GPUs are present. If an AMD GPU is detected, it adds the flag to the boot configuration before the installer generates the boot menu. The check never adds the flag twice, and machines without an AMD GPU never get it at all.

From the first boot of the installed system, CoreCtrl has full control:

  • Custom fan curves: silence at idle, airflow under load.
  • Clock and voltage control. Undervolting an RDNA card is one of the best efficiency wins in PC gaming.
  • Power limit adjustment.
  • Per-application GPU performance profiles.

A note on safety

The flag only exposes controls; it changes no clocks, voltages or fan behaviour by itself. Everything stays at stock until you move a slider in CoreCtrl, and anything you set there can be reverted in CoreCtrl.

A reboot clears any bad setting

CoreCtrl applies profiles at session start (which can be disabled per profile), so the worst-case bad manual setting is gone after a reboot. Defaults are never modified behind your back.

Verifying it works

On a machine with an AMD GPU:

cat /proc/cmdline | grep -o 'amdgpu.ppfeaturemask=[^ ]*'   # flag present at boot
corectrl                                                    # fan/clock controls no longer greyed out

GlouOS applies the same care to AMD processors: see AMD X3D cache mode for how games are steered onto the 3D V-Cache cores automatically.