I don’t know if it answers your question, but I put the above parameters into grub. To temporarily change those, I hit E in the corresponding option into the grub menu on boot (I have a separate disk with Windows too).
I checked the modprobe.d folder and inside there are amdgpu.conf and radeon.conf. Opening the AMD one it says
There are some extra patches coming which might resolve the issue. If you want to test those, I’ve included them in a linux-zen build (5.10.1.zen1-1.0 in my repo, under the testing subdirectory, it works for me).
I searched a bit about linux-zen (as I didn’t knew about it) and decided to give it a try (through AKM).
Since yesterday, everything seems to work fine (I had to install r8168-dkms too).
I’m using Mint 20 and having the same problem as jimmy213. Also Greek, which is coincidence. He got it working with Kernel 5.9.14-zen1-1-zen, but is there an equivalent for Ubuntu based distros?
Don’t know if this will help, but Rolling Rhino is a rolling version of Ubuntu, and may well have the capability to run a newer kernel. Mine’s on mainline, though (and I’m not on it right now) so I can’t check…