Video freeze caused by overheating?

[wanthalf]

Hello, my video display is constantly freezing (if it lights up at all), sooner or later. I tried both my Pine64 1GB and 2GB versions, different displays from the default Pine LCD 720p module to large screen 4k LCD TV. Within a few minutes the screen turns white (or black) and nothing else helps. I did not even manage to start playing any video, just showing the desktop. When trying the 4k video resolution, I noticed it freezes rather sooner and the chip is getting really very hot. I attached a not-so-tiny heatsink to the chip, and the device managed to run at 1080p up to (maybe) some 10 minutes until even the heatsink got burning hot and the picture froze again.

I think I tried all the versions of Android available, from 5.1 to 7.1 (but mostly the 7.1). I am not sure whether I tried some standard Linux distribution with a display as well, at the moment. But without the display, all my Pine64s run continually without problems (and I have one running really 24/7 as a small single-USB-disk NAS, without any problems).

Am I the only one having these problems?