So troubleshot the GF's computer for a few hours.
First it seemed like the PSU was bad, so I put mine in her box. Nothing happened.
Okay mobo is busted? Took everything out sans one stick of ram and booted off onboard video. BIOS came up fine.
Must be the power to the HDD or DVD drive? Hook those up, everything works.
Okay so last thing to hook up, the video card, this HAS to be the source of our troubles. Pop her in, power it up. Everything. Works. Fine.
So what was the problem with the computer to begin with? It was just being an ***.