P5AD2 Premium Won't Post, No Video, Voice Says "System Failed Due to CPU Overclocking"

[vlsl]

Ok, I hope someone can help with this. I just put together a new system:

Intel P4 3.4 Ghz 550
Asus P5AD2 Premium
Gigabyte 800xt Pci Express
WD Raptor 74 gig HD
Corsair 4300 memory

On first boot, the screen said "Bad BIOS Checksum," then it said it was looking for a floppy drive (which I didn't have installed yet), then it looked for a CD-Rom drive and got stuck. Every single boot after that I have no video input to my monitor, and I hear a lady's voice say "System failed due to CPU overclocking." And I'm not overclocking!

I installed the floppy drive, and I've checked the connections on everything. According to the Asus website, it seems as though I should be running Bios version 1006 or higher, and my mobo is version 1002. But how can I flash the bios if I can't even get video to run? I can't do anything at this point because it seems as though my system won't boot at all. It turns on, and I hear the voice, but my monitor says "No video input," although on first boot there was input.

Any ideas?

 

[vlsl]

Just wanted to add an update:

I tried a different video card, and also taking out a memory module (I have 1Gig, matched set of 512). I have reset the CMOS - nothing. What I think would help at this point would be to get back to the boot screen so it can update the bios, but I can't even get a boot screen - there is no video output at all to the monitor. I get nothing but that voice telling me the same thing over and over.

 

[vlsl]

It seems as though I need to update the bios, but how can I update the bios if it won't post?