I dont have anything to attach here, but same issue here, ubun=
tu 19.04, kernel
5.4-rc3, vega64 W/C, Mesa 19.3.0 -- it only seems to occur with DXVK and not
D9VK for some reason.

Example: GW2 (DX9 game) will work perfectly under heavy load in WvW with
massive zergs for hours with no crash, but FFXIV (DX11) will always lock the
entire system up after a time.

That being said, when you force the top clock using

echo manual > /sys/class/drm/card0/device/power_dpm_force_performance_le=
vel

and

echo 7 > /sys/class/drm/card0/device/pp_dpm_sclk

FFXIV no longer locks the system at all. It does eat up a good deal more wa=
tts
according to my UPS meter though, so resetting to auto is necessary IMHO.

So, it sounds like you guys are on the right track with the whole "pow=
er
management" thing being the culprit. Just wanted to add my experience =
to this.

(and yes, echoing the guy above, the exact same system is stable in windows=
 10,
so its not a hardware issue).