I have tested some of the ebay GTX285 cards - they are PC versions of the card that have had their firmware re-flashed with the Mac version.

They come with power cables and drivers (if required) can be downloaded from the EVGA site.

Initial testing alongside a 'real' EVGA card show comparable results and I have had a card running 24/7 for a week now, with no problems.

Contact me directly if you need more information.