try re-seating the video card, memory and if still nothing see if its possible to re-seat the processor (might be better just to give it a bit of a push, than take it off the systemboard)
if not swap the memory around if you have 2 sticks, disconnect the hard disk, dvd rom and remove all the other cards in the expansion slot leaving just the video card, try and power it on now ..
the mother board should only need a processor, ram and a video card to power on..
