# Difference between Mac/PC graphics cards



## macmastah (Aug 25, 2003)

Hi,

What is the difference between Mac and PC video cards?

Thanks


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## DeltaMac (Aug 25, 2003)

Generally speaking, a graphics card sold for PCs will not work in a Mac, and vice versa (some cards can be changed through a firmware installation.) You may find a difference in cost. If the cards are otherwise identical, the firmware installed on the cards will be different, and then, the installed drivers may not provide completely identical functions on both cards.  The various graphics sites that provide benchmark tests sometimes will directly compare a Mac to a PC card. IMHO, there's too many variables to correctly compare identical models on a Mac and a PC.


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## macmastah (Aug 25, 2003)

Thank you very much for the help.


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## Krevinek (Aug 25, 2003)

The two key differences IMO are the drivers and firmware. Because the cards are designed for little-endian operation (nVidia makes chips that can operate as both big-endian and little-endian), drivers wind up doing byte-swapping... which will hinder performance of most ATi cards on the Mac vs their PC counterparts.


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## Arden (Aug 25, 2003)

Explain please: endian, byte-swapping, flashing firmware


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## Krevinek (Aug 25, 2003)

Endian-ness refers to how the 4 bytes (or 8 in the case of the G5) of a value are organized in memory. Big-endian systems are easier to debug manually (it reads like a series of normal numbers), while little-endian systems are there from older design like the x86 and 68k (it takes more time to read through numbers, as chunks are 'out of order' in left->right languages). Little-endian was easier to work with when going from 8-bit to 16-bit chips (Reading from memory was easier to implement from existing design).

Byte-swapping is changing from Big-endian to little-endian or the other way around.

Flashing firmware is taking new software, and putting it into the erasable ROM (usually a FLASH ROM, hence the term 'flashing').

The PPC is Big-endian, the x86 little-endian... and because of the larger x86 installed base, cards are designed to be little-endian. So, Mac drivers usually have to change data from Big-endian to little-endian before giving it to the card. ATi cards perform slightly worse on the Mac platform as a result (it takes time to 'byte swap').


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## Arden (Aug 25, 2003)

Muchas gracias.


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