Seriously hazaky, go and do some (a lot of) reading up on video cards. Come back when you actually know what you're talking about. Your posts are just not making any sense anymore.
The 6850 and 6870 are in the same generation, so I don't know what you're on about. We're talking about rebranding between different generations of cards. Perhaps I should define rebranding so you know what I mean: it's using the same GPU chip/architecture year after year and simply adding more RAM to it and overclocking it a little, and calling it a whole new card.