Do the clean install of the graphics card drivers using the DDU as outlined at the link I posted above. Without doing that first, all we are doing is chasing our tails. That is the MOST common cause of problems while gaming. Once that is done exactly as outlined, we can then begin to eliminate other potential problems but without doing that it's rather pointless unless there is something that definitely jumps out based on hardware behavior.
High temps, overheating, is definitely a problem. A little bit of dust shouldn't cause a system to overheat. It should take an awful lot of dust for that to happen unless your temps are already borderline, then perhaps it might not take a LOT of dust to pass the threshold. I think you need to do the clean GPU card driver installation, then download HWinfo, install it, run "sensors only", open a game that tends to make it crash and take screenshots of the HWinfo sensors. It usually takes about three screenshots to capture all the sensor readings and you need to take the screenshots while the game is running under a load.