Hi. Six weeks ago I bought a 7800GT for my powermac. It Is a mac model. Anyway, when I first recieved it I plugged it ito the 16x pcie slot but did not have the power cable. I managed to get it working by using the 6600LE on one monitor and the 7800GT on another. I kept getting graphical errors on the monitor attached to the 7800, which I realized were due to lack of power to the card. However the card worked, would display a desktop, etc. Just red artifacting on text and such. Edit. Ha. This is where I would have typed "So I bought the power cable." had I better proofread my post. Now I am trying to use the 7800GT alone with one monitor. I have tried many variations of boot order/DVI output but the 7800GT won't allow the system to boot all the way up. I the gray apple screen, the light blue screen, the dark blue screen, and finally the black screen with working mouse pointer. I have tried a PRAM reset and safe mode to no avail. Tried booting into the Leopard install dvd, same response. Is there a proper method for doing what I am trying to do? I am going to try to stick the 6600LE back in there and run two monitors again off two video cards and then pull the monitor cable off the 6600. This seemed to get the cards to work before I had the pcie power cable. Thoughts?