I encountered such a problem that in all games the image on the monitor starts to flicker very strongly, and after a few seconds the computer goes into an energy-saving mode and it does not go away, the problem in the video card (radeon 7770) with another video card does not have such problems.
I have the XFX HD7770 and if I don't install MSI Afterburner, and configure the fan I never have any cooling.
The fans will never cool if I don't, even with the official AMD software.
I have to set it in MSI Afterburner, this work perfectly.
Maybe this is your problem too. Just overheating.