That is a great tip, gonna order myself one of those. Unfortunately nobody sells 'em around where I live, or something like it. So I did it the old fashioned way with a multimeter. All voltages are within the tolerances. So I guess it's not the PSU after all.

So gonna try to do a repair of my win 7 installation, if that doesn't fix it, I'm gonna see if any of my friends are home this evening and try my gfx card in their PC, and if that works I'll do a clean win 7 install.