PSU providing inadequate power could cause crashes, yes, but not likely to cause overheating (unless you could see that the fan wasn't turning...)
When did this start? What temps were you getting before? Did anything change either with the computer or with the surrounding area (new carpet? new house? etc) just before it started? What are the external temps? Is it enclosed in a desk, on top of a desk, on the floor, etc?
Its been going on for about a year now, although the blue screens have become much more frequent than when it first started. If i gamed for 8 hours I might have 3 CTDs before, now its about 1-2 an hour.
It sits in a very open computer stand. I have dogs so I routinely have to make sure that any pet hair is vacuumed out of the case but I am very diligent about that. I am sure the fans are running but I have no idea if the air flow is working as intended, or how I would even really monitor that.
I don't think im handy enough to start messing around with thermal sealant so I am probably looking at replacing the graphics card but before I do that I really want to make sure that the card is the problem and not some other component.
Also in regards to the question about taking out the graphics card and testing for crashes. The ONLY time I crash is when playing a 3D game. When it idles at 75 my computer never crashes so I know its the overheating causing the problem.