I've been running Manjaro for a a few years now and don't have very many gripes with the os opposed to some people that seem to hate it.
The one major problem I have been battling is the random GPU resets under load for my 5600xt. Usually it's when I'm playing semi intense games but sometimes just while watching YouTube. I have seen some things online about power profiles and undercoating but I have not been able to solve it. My only thought now is that it's something with the mesa driver pack.
I am wondering if I were to switch to a distro that supports the official amd drivers if it would be better. I saw pop's new cosmic which looks nice but probably won't be out for while so I'll probably just grab something Debian based with kde, I cannot stand gnome just personal preference. Wondering what peoples opinions are here on this subject.
Give firmware-git a shot. There are some fixes in it that are not in firmware yet.
If that doesn't solve it: for "underclocking" you would have to set a kernel param to enable it. I had a good experience with lact. They also explain the necessary setup in their README. In my case the GPU was running with higher limits than the vendor specified. I simply clocked it back to these specs and it seemed to have worked fine so far. It's a different GPU, though.
If that also doesn't solve it: do you have Windows as dual boot option? Can you try the same games there? If that is also unstable, I would suspect hardware issues.
I think I finally have it all figured out. I was previously using corectrl to monitor and adjust the GPU but lact has so much more info and adjustment. I immediately saw the card flapping between clock speeds under load. I applied the only high clock speeds setting and that all stopped the voltage stayed constant. However and this is why I didn't realize with corectrl is that the card was now thermal throttling causing an undervolt condition. I went in cleaned out the dust bunny's, dislodged a sata cable from one of the fans and relocated some hard drives for more airflow. The card now runs at a toasty 85 under load which from my past amd experience is perfectly fine. Thank you for the help kind stranger.