Acer AM3100-U3201A mobo

I purchased a gforce 7900 dual dvi card when i wanted three monitors up, after buying a 2007 manufactured acer desktop. Then i read my card needs at least 350w to run after i installed it, so i purchased a 500w pwr/sup.

After installed new 500w, i would not get a picture, even after checking connections and rebooting serveraltimes. So i went back to origional 250w and screen lit up installing drivers for model nivia gforce7900 or whatever. So the video card is ok, i can assume cuz even the lil fan on it turned on. Funny cuz card said it needs at least 350w but the origional pwr/spp is just 250w.

I still need the 500w pwer supply installed. So i took it to an idiot friend who was probably stone at the time. So he rigged some wiring forgot to tape up the end and says "i saw a spark coming from your mobo buddy, but i dont smell anything" when i realized one of the stripped wires was hanging around naked near the mother board.

Now my origional power supply is back on and i cannot get a screen signal. The power bottom stays lit no matter how long i keep the button pressed. Also, all fans are running, checked all connections again rebooting it repeatedly, connected and reconnected with no luck. so i got power but no screen signals.

I dont know how to choose a mother board. its a athlon 64x2 chipset 4200+, should i be ok as long as mobo says its athlon64x2 cup. Or can i keep my chipset and install that on just the board. I really dont know how this works, how would i check if my processor is any good. PLEASE HELP! ADVISE ME ON THE SYMPTOMS!!