hmmmmmmmmmmmmmm

I built a computer for my wife's parents this Christmas. 4 days ago, they called me and said their computer shut down while they were playing solitaire, and wouldn't turn back on. Naturally, I assumed it was a power supply and sent them a new one. I instructed my father in law in how to install said power supply and, while he got the computer to power up, the monitor wouldn't display anything. I figured a power surge got his monitor and power supply both, but when he tried a friend's working monitor on his computer, it said "No signal attached" or some such. In addition, the Asus-a7v333 motherboard on the computer beeps once, just like it is supposed to when it's working. This leads me to believe it's the video card that got rocked at the same time as the power supply. But why? Why would a power supply and a video card go out at the same time?

Anybody have any ideas about this?