A Beyond3D forum member leaked pictures of what appears to be an engineering release of Radeon HD 7900 series Tahiti cards running in CrossfireX.
The specs are still unknown but looking at the picture reveals a thing or two. The card is pictured from behind, and its pretty much clear it comes equipped with a total of twelve memory chips, which confirms the rumored 384-bit memory interface.
Another interesting thing are the PCI-Express power connectors, the card will need one 8-pin and one 6-pin PCI-Express power connector. Just remember these are engineering release cards and the final version might be slightly different.
We should expect more leaks and details pretty soon.