[geeks] PCI-E video cards

[nate at portents.com]

> Correct me if I am wrong, but you can only flash Apple EFI ROM onto
> cards that are very close to something Apple sells.
>
> In other words, you can't flash an nVidia 7900, because Apple never
> sold one and thus never made a BIOS for it.

That's right.  Since a video card's firmware handles initializing the GPU,
initializing the VRAM, and providing a table of fan speeds for GPU
temperatures, the type of card does matter.  Some cards are very similar
(like the 6800 Ultra and the 6800 GT), however other cards can be very
different (like the 8800GTS 640MB and the 8800GTS 512MB), and then OEMs
have the option of creating custom hardware/firmware combinations which
can deviate even more.  And there are generational differences, i.e. the
NVIDIA 7900 series firmware architecture differs significantly from the
7800 series (it took a number of months for the third-party Windows-based
NVIDIA BIOS Editor, NiBiTor, to gain support for editing the 7900 series
firmware).

The closer to the NVIDIA/ATI reference card designs that Apple uses, the
better the chances (though for a while Apple was including DVI dual-link
TDMS transmitters that you'd only find on higher-end FX/FireGL cards which
made matching things up even more difficult).

- Nate