You have a very good question!
Will HD5970 be faster than two HD5870 in Crossfire?
We won't know until its tested, I guess. And, we know someone has probably already done the test under NDA and may publish on Wednesday.
Yes, it looks like they have not got the "2 GPU look like 1 GPU" circuit on this card. Perhaps, they improved the small amount of circuits they had on the HD4870 X2, perhaps not. I guess we must await that answer too -- maybe Wednesday if a "top site" does the report. Still, if they have improved the HD4870 X2 circuit, it might make the HD5970 faster than two Crossfired cards. If they haven't, then I am guessing 2 separate cards will be faster -- and probably more expensive.
All speculation on my part. I'm not predicting any particular outcome

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