Well, the somewhat standard procedure is to take out all the cards except the vid card and ram...pull out all the ide cables from the motherboard.
Then maybe reseat the ram and video card.
Try it like that.
Or just try reseating the ram and video card first and then try unplugging the ide cables and other stuff to narrow the problem down.
Some motherboards have a jumper that has to be moved before you can boot, maybe its the bios jumper. Some pc chips boards are like that i think, they will NOT boot out of the box before you move the jumper.
JP