If parts have become heat sensitive. I don't want to upset folk but the test is only that, to sniff out if there is a chance that we can find something to fix the issue. That is, there are too many stories from the shop to share about this one. I'll keep is to one where the heatsink had lost one of the four retaining pins. The owner/builder didn't think it mattered and the result was a heatsink that was just hitting the one side of the component it was cooling. To make matters harder for everyone the owner was adamant it was not heat because of some temperature readout software.
The case cover off and fan was in that case showing it was heat related so we checked all the parts again, found the missing retainer and pin then applied a little compound and buttoned it down. Kind of a shame to see the bill for 200 all because they thought the last retainer/pin was optional.
Anyhow, the lesson repeats too often. Don't trust those temperature software readings and get very familiar with those heatsinks and how they are held in place.
ALL THIS was to explain why we do that test. If it gives you an idea then good. But ONE last idea is to check for video card driver updates from the card maker and then swap out that card.
AND if you can connect with HDMI, that helps remove an issue with VGA.