Hello, I recently purchased the XFX HD-487A-ZWFC Radeon HD 4870 1GB from Newegg to flash and use in my 2007 Mac Pro (2,1). I have tried flashing the card several times, but with not that much luck. First of all, here's my setup: 3GHz Quad-Core Intel Xeon Mac Pro 2007 (2,1) 8 GB Memory 10.6.4 with recent graphics update 30" Apple Cinema Display (2560 x 1600) I am upgrading from the Nvidia Quadro FX 4500. I have a spare Nvidia GeForce 7300 GT card that I am using while trying to flash my new ATI Radeon. The first thing I tried was booting with the Radeon in slot 1 and the GeForce 7300 in slot 4, using the latter for the display. No luck, I just got a blank screen. I have an older Alienware PC that can successfully use the new Radeon card (although due to it's age I'm guessing it's probably only 2x or 4x power). I downloaded the latest version of Winflash, but that said it couldn't replace the ROM so I went with version 188.8.131.52, which was linked to in this guide. I decided to try and flash using Naaaaak's modified ROM, since it sounds like my graphics card is the same. The Alienware only has one PCIe slot, so I was flashing the active graphics card. Winflash showed the message "Programming VBIOS: Please wait. Flashing is in progress, it may take more than a minute....." with an 80% progress bar for about an hour, and then it reported that it successfully replaced the VBIOS. I put this graphics card into the Mac Pro and plugged my display into it as I booted the screen showed a lower-res version of the standard grey Apple logo, and the computer was able to boot in 1280 x 800 resolution. I installed the latest ATI drivers through Cindori's Zeus tool, and restarted. Upon restarting, I got the low-res Apple logo again, but then a blank screen after a few seconds. I put the computer to sleep using the power button, and after I woke the computer back up the screen came to life in full 2560 x 1600 resolution. Sounds like a happy ending, right? The card was fully recognized by the Mac, with full resolution and everything. As I moved my cursor through the dock it was quite laggy/choppy. Portal couldn't start since it claimed that my system didn't meet the minimum system requirements (although this isn't the case). StarCraft 2 claimed that it was missing certain files so it couldn't start and required a reinstall (it could and has started fine when I use the 7300 GT). Based on the Expansion Slot Utility that popped up, the Radeon card was at full 16x power (the utility only showed up because my GeForce 7300 was not at full 8x power in slot 4). So although the graphics card seemed to be supported fine in theory, it didn't seem to be gaining it's full potential. I decided to create my own ROM and give that a go. I followed the instructions in the XYZ.zip from Cindori's Golden Guide. During the process, I ran into some issues with specifying the directories in the terminal code, but I was able to generate a modified ROM that seemed to be fine (it has two MCuC's). I just successfully flashed this new ROM I created, using the older version of Winflash on the Alienware. The Mac Pro displays nothing when using the Radeon graphics card for the display. And it is a little buggy when I have it inside while using the 7300 GT for the display it recognizes both graphics cards properly in the Graphics/Displays tab of the System Profiler, but reported an error that it was unable to display PCI information when I changed to that tab. I'm getting slightly frustrated at my current flashing state and current progress. I would love to hear any sort of help/tips you guys have. I've attached my original ROM as well as the modified one I created, and my graphics card info from GPU-Z. If someone could try and whip up a modified ROM for me, or take a look to see if my modified one is bad, that would be great. For future flashing trials, would it help if I first flash my card with the original ROM to restore it before flashing with a modified ROM? Or can I just go ahead and flash the modified ROM like I've been doing? Thanks for your help!