Having trouble installing flashed sapphire 487

EDIT: sapphire 4870

Hi, i recently bought a Sapphire Radeon HD 4870 512M GDDR5 PCI-E DUAL DVI-I/TVO SKU# 21133-00 S/N 180825044742 flashed with mac firmware.

The instructions said to take out my existing card put the sapphire in slot 1, then boot up and install drivers.

So i took my Nvidia 7300 GT card out of slot 1 and put in the 4870, then started up. I get the grey start up screen with the apple in low resolution for about 8 sec, then the screen just goes blank.

What am i doing wrong?... do i need to keep the Nvidia 7300 GT in slot 2, then boot up connected to that first?

Im really frustrated. Could someone please help me? It would be greatly appreciated.

Thanks.

Did the Sapphire card come already flashed for use in a Mac or did you update and flash the new firmware yourself? The reason I ask is that it sounds like the card is not compatible - possibly because of a bad firmware flash update. (The symptoms you describe point to a graphics card problem.)

Flashing a PC graphics card with Mac firmware so that it can be used in a Mac is iffy at best. Sometimes it works and sometimes it doesn't.

Also it would help if you could let us know which Mac (model and year) you're installing the Sapphire in.

Regards.

Im running a Mac Pro 1,1

The card was pre flashed from a guy that was using is successfully in a Mac Pro 1,1. I've never installed a graphics card, so i'm thinking the problem may lie on me end.

Right now, im running with the 4780 card in slot one, and the Nvidia 7300 in slot 3. Do i need to install drivers, then re boot connected to the 4870? If so, where do i get the drivers?