Here is the standard procedure for flashing ATI cards in PC if you have a suitable Mac ROM for your card.
• Download the Mac ROM intended for your PC ATI card from The Mac Elite, here :
• First of all you will have to make a DOS bootable disk (or USB flash disk if your PC supports booting from USB) and copy over atiflash.exe, along with the BIOS you choose to use.
Latest ATIFLASH program can be found at http://www.techpowerup.com/, you will also find there a huge ATI ROM collection for PC card (and even some Mac ATI ROMs)
Latest ATIFLASH (3.10 and above) supports flashing 128KB ROM if your card has a 128KB rom chip.
• Flashing with ATIFLASH 3.10 and above:
After you created the bootable disk, restart your PC with the boot disk. At the command prompt, type the following and begin your flash process.
a:\>atiflash -i [Enter]
Will check the system for ATI cards installed. If there are several, they will be numbered, counting from "0". Check out whichh is the card to be flashed.
a:\>atiflash -s backup.rom [Enter]
Standard back-up (saves BIOS to Floppy/current directory)
(note : "a:\>" might be a different letter if you're booting from anything else than a floppy disk. USB "Pen Drive" will work as standard Hard Drive and command prompt will probably look like "c:\>")
a\>:atiflash -p 0 mac.rom -f [Enter]
-p is switch to program the rom.
0 (zero) is the adapter number, if there is only one card installed. If you have 2 ATI cards, check first which adapter number is the card you want to flash (see above).
mac.rom is the Mac ROM file you want to flash to your card.
-f is the switch to allow forced flash for different ROM revision or if there's a DeviceID mismatch between PC ROM and Mac ROM
If everything is fine, you should get a message telling the flash process went fine.
If you get an error message, flash your card back to PC ROM to avoid being stuck on PC reboot with a misflashed ATI card.
This flashing procedure should work with almost every ATI card which has a known working mac rom (original or modified, full 128KB or reduced to 64KB)
Check ATIFLASH DOS command line help to get full switches and options list as it depends on the version of the ATIFLASH program you're using.
FLASHROM DOS command line program also has equivalent features. However, it is not supposed to work with 128KB Mac ROMs.
If a 9500 or 9700 does not work on the Mac, check whether it requires separate power supply (PC-floppy-disk-power-connector opposite side to the VGA plug).