While testing the new 4870x2 ROMs I booted into WIndows and played some Halo 2 for 5 minutes or so. When I was done as I started to exit Halo, the computer abruptly turned off. It had done this before with 4870x2 playing Crysis so I thought little of it. I tossed a 3870 in to do some fiddling and it booted normally. I went to run errands and returned to wake machine from sleep. After a few seconds it shut down. I rebooted and halfway through boot it shut down again. Now there is NO response from anything...the mighty Mac has died. There are no LEDs on anywhere when plugged in so I am hopeful it is the Power Supply. DVWharehouse has them locally for $280. Guess I'm getting one tomorrow. Meanwhile, I think I may sell my 4870x2. It always seemed the Mac Pro was at the end of it's limits running the beast and perhaps the new 3.0 5160s in concert with warm weather and draw of 4870x2 were too much. The card was powered via the 2 logic board connectors. Does anyone have a link to the 2006/07 service manuals? Hoping there is a magic "reset button" but realistically.....not.