I have the following Mac Pro: MacPro1,1 Dual-Core Intel Xeon 9 GB RAM OSX - Snow Leopard 10.6.4 (with graphics update) Dell 2208WFP 24" monitor And I'd love to use the new XFX ATI Radeon HD 4870 (ZWFL) in it. I've been diligently trying to follow the guides and advice found here, but I'm getting nowhere, and I'm starting to wonder if I have a hardware problem. I installed the card into slot 1, and moved my GT7300 to slot 4. I plugged the power cables into the XFX. I was hoping I could flash it using Zeus, but when I turned on the Mac, and tried to boot to OSX, I got a grey screen of death saying "You need to restart your computer. Hold down the Power button until it turns off, then press the Power button again." Then I booted to Windows Vista (boot camp). The only way I could get GPU-Z to give me info on the card was to install Catalyst drivers, plug the monitor into the XFX card, and force boot camp to restart to Windows. Once Windows restarted, GPU-Z gave me all sorts of info, but will not save the rom. It says the BIOS won't let it save (I can't recall the exact error, sorry). Then I got ATIFlash 3.79, went to a command prompt, and typed "atiflash -i", and was disappointed when nothing listed. On the positive side, while I was in Windows using with the XFX card, I was able to play Supreme Commander, and it was silky-smooth. I've tried over and over, and I can't even get to a point where I can flash it. I've tried unplugging and removing all peripherals, including extra internal hard drives. Am I doing something wrong, or am I looking at a bad card? It seems from the messages here that it should be much easier than it's been so far.