I'm using an AMD RX 5700 XT GPU on my system for over 6 months now, using the open source drivers. It works fine.
But I need to do some Machine Learning stuff, and ROCM doesn't even work on this card yet. So I need CUDA.
Luckily, I have an older nVidia Geforce GTX 970 lying around. So I installed it.
When I rebooted, everything worked fine. Both cards were detected and working.
Then I installed the proprietary nvidia drivers.
Now GDM tries to start on the GPU card, but fails. It tries to start an X11 session too (I'm actually using wayland, and want to keep using wayland)
So after it keeps on trying to start GDM/X11 on the nvidia GPU, it stops trying and finally shows me a console. All output on my AMD GPU, btw.
So the question is: how do I tell the system/GDM to leave the nvidia GPU alone and just keep on using the AMD GPU?