RegistryDwords perf level limit ignored when modesetting is used?

I use the following xorg.conf option to limit my GPU to a low power profile:

Option  "RegistryDwords" "PowerMizerEnable=0x1; PerfLevelSrc=0x3333; PowerMizerLevel=0x2; PowerMizerDefault=0x2; PowerMizerDefaultAC=0x2"

However, when enabling modesetting by adding this in the kernel command line:


then the driver ignores the power limit configured with RegistryDwords.

Is this intended, a known bug, or is it just me? I need the perf level limit to keep the GPU fan at 0RPM and reduce noise when booting to Linux for work. I don’t need performance as I do not run games when booting to Linux.

Using driver 455.38 on Gentoo Linux 64-bit with a GTX 980 Ti.