I have a 2006 MP 1,1 and the Radeon 5770 works just fine. No glitches. Installing it was easy but I was surprised to find the metal plate on the right of the card does not line up well against the MAC housing so I couldn't screw the PCI bracket back into place. I reinstalled the card several times and it looked perfectly set, yet the holes on the right did not line up very well (almost but not perfectly). I was finally able to muscle the top screw in enough and tighten down so the PCI bracket could be secured (couldn't get bottom one in). Turned MAC on and everything is perfect. Anyone have that problem with the bracket reattachment?? Tonight I want to install a new LG (LGEUH12LS28KMPL) blu-ray drive from OWC (with Mac Pro 1,1 cable kit). The instructions make it look like a long process with multiple steps. It says I have to remove everything (hard drives, memory cards, video card (and that pesky PCI bracket I BARELY got back on - now have to remove again), fan assembly and memory bay. Wow! I've added hard drives, memory and graphics card recently but this looks pretty involved. You think a newbie like me can tackle this one myself?? Any inside tips would be appreciated!