Try removing each ram stick individually and booting, and test the video card, either in another machine, or with another card. If you still don't have a fix, try a different power supply. If none of these work, I hate to say it, but the motherboard is probably dead. The quality control on some of those OEM motherboards is atrocious. Also, can you get me the amount of ram, ram sticks, and at least the CPU manufacturer, line, and frequency?