We were dreaming about it, and Netkas did. Originating from the Hackintosh projects, those "extensions" can be installed on most PC version of Radeon without requiring to flash the BIOS of those cards. How does it work? In summary, those extensions include part of the EFI code required for the card to be recognized by the Mac and to have them active in Mac OS X. Hereafter are results obtained after installing a Radeon HD 4890 PC version in a Mac Pro 2008:
Hereafter is the procedure to get to this point:
Install Radeon HD 48x0 drivers shipping with Mac Pro 2009: http://www.sendspace.com/file/gvsi12
Install extensions allowing recognition of those PC version cards: http://rapidshare.de/files/46982841/A
