2007 Mini artifacts

I have a 2007 Mac Mini at work that we're trying to figure out what's happening to it. We were trying to boot it one day, and we got a kernel panic in which we rebooted it, and now we get screen artifacts on the 1080p screen we had hooked up. I'm going to run some more tests on it tomorrow when i'm back in, but preliminarily, what does the problem sound like?

Failing or over heated graphics chip. Have it cleaned out of all dust reapply new thermal paste to the heat sinks .

It's interesting, i had it tested today, and the display worked for a little bit, then shut itself off, so it might just be an overheating issue. How would i go about reapplying thermal paste of that's the case?

I don't have a specific method with the mac mini Ive never had one to take apart before.
If it were me doing the work it would be a learning experience lol . I have had so many computers apart in my life time it just kinda comes naturally to me anymore.
That's why I suggested taking it and having it done, but you could attempt it if your comfortable with disassembly of computers. I can however get you as far as the logic board removal as I believe the entire board needs removed to access the screws that fasten the heat sinks to the board.
ifixit has several models of mac mini units and how to disassemble them . with out knowing what exact mini you have I can only link you to the mac mini menu of ifixit from there youll have to select your model and do some reading . ifixit is a great place for all kinds of electronic device repairs as they include complete tool lists and step by step instructions for various components including pictures.

Mac Mini Repair - iFixit

Well, i'll take a look at the ifixit guide and take it apart. I'll let you know once i get to the heatsink and we'll go from there. Thanks