AIB GPU factory-OC power limit (405W) capped at reference TDP (339W) on SteamOS / amdgpu

[julienchabanon]

Hardware:*

• GPU: Gigabyte Aorus RX 7900 XTX (factory-OC model, 405W rated TDP)
• Motherboard: ASUS ROG X870
• OS: SteamOS 3.8 (kernel 6.16)

Description:

My Aorus RX 7900 XTX has a factory TDP of 405W (not a user-applied overclock — this is the card's stock power rating as shipped by Gigabyte). Under Windows the card pulls up to 405W under full load. Under SteamOS it caps at ~339W.

Inspecting the sysfs hwmon interface:

/sys/class/drm/card0/device/hwmon/hwmon9/power1_cap        = 339000000
/sys/class/drm/card0/device/hwmon/hwmon9/power1_cap_max     = 350000000 (read-only)

Writing 405000000 to power1_cap returns Invalid argument, and power1_cap_max is read-only even as root (Permission denied).

It appears amdgpu reads the reference power table and caps at the AMD reference TDP rather than the SPPT/VBIOS value of the AIB card, unless OverDrive is explicitly enabled via the amdgpu.ppfeaturemask=0xffffffff kernel parameter.

Question / request:

Is there a supported way on SteamOS to have amdgpu honor the AIB card's factory power table without manually setting ppfeaturemask and disabling the read-only filesystem? Setting kernel args on the immutable SteamOS image is fragile and may not survive system updates.

This affects other factory-OC AIB cards too (Sapphire Nitro, PowerColor Red Devil, etc.) where the hardware's rated TDP exceeds the AMD reference value.

Steps to reproduce:

1. Install SteamOS 3.8 on a PC with a factory-OC RX 7900 XTX
2. cat /sys/class/drm/card0/device/hwmon/hwmon*/power1_cap_max
3. Observe the value is the reference TDP, not the card's rated TDP

[TheGeekno72]

as a temporary fix, is it still locked to 339 through the use of LACT? (flatpak available in Discover)

I was already able to change the power limit up and down of my 9060XT and the most recent updates allow for further tweaking (voltage & clocks) now