If those numbers are correct, these cards are double in term of efficiency.
Not really, more like ~0% stock and ~ +30% undervolted at stock clock vs. my old 5970 numbers here.Guess we'll never know why on earth AMD decided to go with 1.175V core at 925 MHz, so far all cards seem perfectly happy at 0.95-1.05V at 925 core for mining and 3D. While at stock V they seem to OC to 1050-1120 MHz...
Now the big Q: if those aren't cherry-picked chips, what will 7990s be able to reach?
A little bird told me AMD is kicking themselves for clocking them too low.
Nah, you forget these are the reference cards. They need to leave headroom for the card makers to put out their factory overclocked and otherwise special edition cards.