Just a very short note. Anyone experiencing difficulties with the above hardware. The symptom is complete hard locks in X11. They happen every hour or two, seemingly without any cause. No kernel logs, no errors, no response to anything. If music is playing it will hang and loop the same 2-second snippet. It's exactly like a kernel hang, except without any diagnostics remaining after reboot. Most people suggest hardware RAM issues, but I've run checks on both regular memory and GPU memory.

I don't have a solution, but I do have a workaround that I found in a thread on MXLinux forums. The workaround is to downgrade the 4.19.x kernel to the 4.9 kernel. Horrible, I know, especially as the 4.9 kernel has actually been removed from Buster. I think that I only had it around as the remnants of a previous dist-upgrade from Stretch. Frankly I don't know what the best procedure for dealing with this is, but I can say that this is the only thing that worked, having tried tons of X11 config hacks, nothing made any difference. I just have to hope that this issue will vanish in a future kernel release. :/