Comment # 30 on bug 75992 from Egon Ashrafinia

"echo "high" > /sys/class/drm/card0/device/power_profile" crashes me too when I
try to set it after "radeon.dpm=0".

Because the default one is really on a low level. No OpenGL animation works
smooth.

My hole Display turned black, but the computer was still turned on. ... No
reactions anymore. Hard Restart required.