checked your temps???ram set for auto[spd],i have the non sli of the m2n mobo,and when i was putting it together i noticed that my crucial ballistic ram was not on the QVL list,,but,, the recommended ram did not work very well the mobo only puts out 1.95 voltage for the ram which is rated at 2.20...HMMM..you might try another psu just to eliminate that possibility..
i was sick of waiting and guessing, and i bought a Phenom 9950 Black edition quad core processor and a new M3N72-D Asus board. Booted fine and everything with the video card, i went to get the x64 updates for windows xp, and restarted the machine, and bang. EXACT same problem.
So i'll be getting on the horn with EVGA concerning this matter. gonna take about 3 weeks or so to get a replacement card -.-