On Ubuntu the kernel log keeps appending to /var/log/kern.log, but that might
look different on different distros.

If you have a luxury of a second system you might be able to ssh into the Ryzen
system and run dmesg that way.

As for the options Edward mentioned, you can pass them to the kernel command
line. If you use grub for your bootloader you'd press 'e' on the selected
kernel and append " amdgpu.dpm=0 amdgpu.dc=1" at the end of the line that
starts with "linux". Alternatively you can append those to GRUB_CMDLINE_LINUX
in /etc/default/grub and run "sudo update-grub"

Keep in mind that this is how I'd do it on Ubuntu. There' might be a way to
pass these through /etc/modconf.d as well.