So I recieved my 4890 today and made it work fine in my Mac Pro with 2nd superdrive as power source. Then I went ahead and installed a Accelero Twin turbo cooler. I took power from the second superdrive for the cooler in addition to powering the card itself. Upon boot I had no display, no fan movement for 5 sec then all the fans in my mac pro started climbing in speed and stopping on 100% like a turbo jet. So black screen and no matter what card I use (4890, 8800gt, 7300gt) with superdrive power disconnected, still black display and full tilt fans. Is my power supply broken? did I somehow overload it? im guessing this is a issue for my apple store but in a last attempt on saving alot of cash and 2weeks without computer I am asking you guys.