Just built a new PC this afternoon, and I can't get it to POST. When I turn it on it powers up and all the fans start spinning, but I get no video. I also get no beeps from the system speaker (it's supposed to beep once if everything is ok, and one short and then three long if it can't detect VGA). Also, even though the power switch will turn the PC on, it won't turn it off no matter how long I hold it down for (this includes both the case switch and the one built into the MB). The only way to turn it off is to flip the PSU switch to cut the power. Finally, the build in LCD Poster thing that came with the motherboard is no help. It displays welcome when first turning on, then just starts counting up. No messages at all. Here's a list of all the hardware, and I'd really appreciate some advice on what to do. It's been almost 5 years since I built a PC, so my troubleshooting is a little rusty.
Motherboard: Asus Rampage II Gene
CPU: Intel i7 920
RAM: 6GB OCZ DDR3
Video Card: Sapphire Radeon 5770 w/ Vapor-X
DVD Drive: Lite-On Dvd Burner