I am rebuilding my little bro's computer and it decided that it does not want to turn on? I installed a new geforce 7800 gs video card two dvd drives and another hard drive. I made sure that one was a slave and one was a master. It is an older comp. it is a pentium 4 with a 300 or 350 ps, think its socket A, 1 gig of ram. I know the power is working because the motherboard has a light on it which lights up whenever i turn the ps on. I have tried to disconnect both the dvd drives and it still did not trun on???? I neeed some help!!!!!!