PNY 9800 GT & Gateway DX4822: No post screen or beeps

Hello-

video card: PNY 9800 GT (powersaver... no 6 pin plug on the back)
computer: Gateway DX4822

First off, I've already put in a Corsair 650w PSU to handle the amperage. When I insert the 9800 card I get NOTHING. No post beeps, no post screen, no booting into windows. No lights on the keyboard, etc. When I take it out and revert to onboard video it boots up fine.

I have tried inserting an older 7800 GT and I can hear it boot into windows & the keyboard works but I still have no video.

I've checked all the cables, don't think I'm missing anything stupid. What could it be? I'd guess bad video card but why doesn't my older 7800 work? This card was working in my other computer.

Thanks.

edit: I've already tried switching the BIOS to use PCI-E as the primary device. This does nothing. I read elsewhere that 'auto' (the default setting) shuts off onboard as soon as it detects another graphic device anyhow.

Additionally, when I insert the card and hit the power button the computer will power cycle (by itself!) 2 times, on the 3rd it will take and stay on. Odd?