The power supply good or not? Can try to change to another power supply if you have extra. Sometimes mobo got light doesn't mean power supply is ok. If you dont have spare unit of power, you need to jump start it with green and black cable.
Better still just plug out all the cables or graphic card. Just mobo and power supply only.

http://www.instructables.com/id/How-to-pow...y-without-a-PC/