You could try is this:
It enables some features, which are not present by default.
Or it could be frequency problem:
https://wiki.archlinux.org/index.php/AMDGPU#Screen_artifacts_and_frequency_problem
set the gpu to high:
sudo echo "high" > /sys/class/drm/card0/device/power_dpm_force_performance_level
set the gpu to low:
sudo echo "low" > /sys/class/drm/card0/device/power_dpm_force_performance_level
with
watch -n 1 cat /sys/class/drm/card0/device/hwmon/hwmon*/temp1_input
you cant watch the temperatur of the gpu directly.