I think your asking what component the spark originated from, correct? To find this out inspect the parts for burned/black capacitors etc. You should also check the various components with a multimeter.
i'm assuming u were just building this comp...if so i feel very bad for u and now i'm am afraid to make my own cuz it seems like so many things can go wrong that u cant control
No...the comp was already build...the mobo was defective, but I decided to keep it...here you go: a fried mobo...yours will be OK, but if there is a problem...take it back