What is Zeus?
Zeus is a Mac GPU Flashing Tool. It can write a new firmware on to your graphic card.
But it can do much more then that. You can patch your drivers to add support for excotic cards, install injectors by Netkas, and save the firmware from your Nvidia card.
Zeus is the replacement for ATI Flashing Tool.


Thanks
My thanks to specially, Netkas, Rominator and Pipomolo for providing with key elements in creation of this app.

My even more special thanks to Donaters, for without them the app would have stayed at ATI Flashing Tool 1.0

HOW TO FLASH:
Nvidia:
Flashing and Dumping Nvidia only works on the Nvidia card in the bottom slot. It’s recommended not to use these functions with two Nvidia inside the computer.
1. Open Zeus
2. Select Nvidia tab
3. Browse for ROM
4. Click Flash


ATI:

1. Open Zeus
2. Select ATI tab
3. Select OS
4. Browse for ROM
5. Click Flash

source: Zeus