Im pretty sure all other 8800gt other then apple's one have 64k EEPROM chips, however i may be wrong.
Sorry if against the rules but you should be able to find a reduced size eeprom file that you could flash onto the card and thus enable it to work.
My mistake have found this, links removed due to competitors
"Success flashing PC 8800GT card for 2008 Mac Pro
Just thought I'd pass along the fact that I was able to successfully re-flash an EVGA brand nVidia 8800GT video card for use in the latest version of the Mac Pro.
Apparently, this often is not possible because Windows PCs only require 64K of flash memory on the card for the video BIOS they use. The Mac, however, needs a 128K flash memory chip on the card, since it has the EFI64 data AND the BIOS information stored on it. Furthermore, I understand this only works when the EEPROM ID has an "MX" on the beginning of it. Flash chips marked with a "PMC" on them won't work, even IF they're 128K.
The specific EVGA board does have the correct 128K flash chip on it ("eVGA e-GeForce 8800 GT 512MB DDR3 Superclocked Edition PCI-Express Graphics Card (512-P3-N802-AR)" - $254.99 before $30 rebate.)
The only other issue I had after flashing it with a ROM image taken from a Mac 8800GT was the power connector. The PC versions of these cards ship with a different power connector than the square type that plugs into the Mac Pro's motherboard for aux. power.
The power cable sold for the ATI X1900XT card fits it perfectly though, and they can be ordered from ATI's web site for about $18 shipped (at least anyplace in the USA).
Since my Mac Pro was originally ordered with the ATI 2600 card, going this route got me working with an 8800GT upgrade much faster than the 7 weeks shipping delay on ordering the real Mac 8800GT from Apple Ï plus it saved me about $50. (The Apple price for the Mac 8800GT card is $349 for those that didn't spring for the $200 CTO 8800GT option originally)
-Tom"
