I built a new machine with these components: Antec SX635 (350w) case, Asus A7N8X nforce2 mobo, AMD XP 2700+, 512MB Geil PC3200. When I start the computer, all components power up but there is no video. I've tried a different mobo, processor, memory, video card, and monitor, with the same result. I've tried removing the video card and memory to verify I get a beep sequence, but I don't. I've double and triple checked all connections. Any ideas as to what the problem could be?