I've seen that before. It could be as simple as a loose connection or as bad as what you suggest.

I've seen this hooking up external monitors too.

This is one of those things where it is worth taking apart your notebook and checking every connection inside.

I took apart everything, even opened up the copper casing of the card itself. I've tried cleaning all the connections with compressed air, but it's still the same. I probably pushed it by switching it on despite the laptop crashing and the lcd dying.

interesting, cause I just started getting these same artifacts in my 8790