I just upgraded an HP P6210Y to a 500w power supply to support my new GTX 460. The power supply went in fine, hooked up the two 6 pin plugs to the card, the fan on the video card spins up, but my system just isn't identifying that the card is there. As with newer P6210Y's I don't have a bios option to switch cards, resetting the bios does nothing, and device manager shows nothing. I'm very sure it's plugged in properly; I gave it a firm push and it fits snug.
Straight out of the box? I haven't had that one happen to me in years, but I guess it's possible. I'll get it tested tomorrow. If you or anyone else has other ideas, I'd love to hear them. Thanks for the help so far.
After taking the computer to a friend and in for a diagnosis at a local shop, it turns out I'm an idiot. The card sits in just beside the tabs for the ram, I had it just above, so the entire thing was seating just a hair off in the slot. Problem solved.