Flashed PC Radeon HD5870 in a Mac Pro 2008

Several team members own a Mac Pro 2006 or 2008. So, in addition to Guillaume, several of us are trying to graft a flashed PC Radeon HD5870 in their Mac Pro. As previously described, we initially selected the XFX HD5870 1GB. Today, we tried to repeat the procedure with a Sapphire Vapor-X.

This card is slightly more expensive than the first one, but offers an improved ooling system. The procedure remains the same for flashing and installing such PC card in a Mac Pro:

1. Download the iso image of Freedos. The basic version will be more than enough. Burn the iso image on a CD with your disk utility.
2. Create a FAT32 partition on one the HDs of your Mac Pro. It has to be in MBR (and not GPT), otherwise Freedos will not boot.
3. Download the last version of ATIFlash and the ROM corresponding to your graphic cards (here: m5870sap.rom.zip) from Netkas site.
4. Unzip and copy all files to the FAT32 partition.
5. Load the iso image containing CD and siwth off your computer. If hte CD is ejected, insert it again just before the current is switched off.
6. Install the Radeon HD5870 instead of your current graphic card and plug different Molex plugs.
7. Reboot while holding down C key. When asked, using the numerical key pad, activate it (press on the key over the "7"), then press "1" and validate. You will have to press key "2" when asked o nthe second screen. Now you are running Dos. Be careful it is now a QWERTY keyboard. 
8. Type C: to move to the C: drive on which are located all files for the flashing procedure.
9. Type atiflash -s 0 orig.rom 20000 and press Enter to save the original ROM of your card in case of problem.
10. Type atiflash -p -fs -fp 0 m5870sap.rom and press Enter to flash the graphic card. There should be no other graphic cards installed in your computer.

That's it. Reboot by forcing the procedure (maintaining the power button down for more than 5 seconds), then you have to be patient till the card is recognized by the system:

To test the card, we have launched Starcraft II with all graphical rendering pushed to the max (2560x1600). we could detect some small slow down from time to time, butthe game remains fluid, something impassible with a Radeon HD4890 even with its GPU overclocked to 1 GHz.
Maybe with some luck, we could make this card natively recognized from booting, but it remains only a small feature when considering how it revives a 2 or 3-years old Mac Pro.