ok ya ready to try to fix this thing?? couple of things first...when you hit the power does it start and then shut right back off?? if so you got power..so i would firstly swap your memory sticks around into different slots...then reset the Cmos...unplug the main power cord from back of the pc most newer boards have a reset button on the board itself if not just take out the battery for a few seconds the put it back in { battery looks like a big watch battery}...plug it back in and see if that helps, if not your PC maybe instantly overheating which i would try new thermal compound on my cpu before i went and bought a bunch of new shit..then if that doesnt work...try removing the video card and connecting to the onboard video if the MOBO has on board video and even if it doesnt try taking the vid card out and starting the machine and see if it stays running or not...just a few tips to try before ya go and spend a bunch of money. hope this helps out some. LaterZ

you may want to try to add your memory back 1 stick at a time ,and make sure if you do that you put them in in the way the mobo manual suggests.