Note
This is my personal workaround to the nebulous [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx_0.0.0 timeout
which I have not experienced since the first day, after many months of trial and error, that I started using these exact settings, albeit with older versions of Gentoo's LTS kernel and stable graphics packages, on May 7th 2023, 1 year and 4 months ago. Some people claim that the situation on RDNA2 and RDNA3 is different, so if you have a similar but non-RDNA1 GPU, you might be able to find similar but slightly different workarounds for your system in that freedesktop gitlab issue.
Important
During my 1 year and 4 months test, other Gentoo users have independently and simultaneously discovered and written in-depth documentation for the same/equivalent procedure into the Gentoo Wiki, creating a more c