as stated earlier my Bro fixes these probs everyday he will be coming over this weekend, if Nathan doesn't help you fix it I can show him this thread and he may be able to help but so far it sounds like Nathan is making all the right moves, have you tried to start it with everything unplugged, drives, video card, sound card etc just run with the neccessities ( i know you did it with video and ram). be careful introducing different parts into it as if something is spiking in it you could also damage the new parts also.