Q6600 no video

Strange, I just rebuilt this machine changing out the stock HS/F and the PSU, just died overnight. It has worked well for a week. It seems to boot up when I hit enter on the unseen multi-boot screen, makes all the right noises too to the point of it taking the normal 4 secs to re-boot from the front panel power switch as if the OS was running. Changing out video cards didn't help either nor did bypassing the KVM.

Anything here that I've missed? Thanks.

EDIT: ASUS P5Q-Pro, 2X 9800GT

 

Oops, I forgot to mention that I had to reset the BIOS time several times as it kept losing it every time I booted before. Could the battery prevent me from booting even into the BIOS or see the same on screen? At any rate, this machine is 4 years old and I'm getting a new battery just because they're inexpensive. I hope that's all it is.