The card has been tested under full load pulling 192 watt by a hardware review site who had their hands on the first cards
That full load was doing a heavy game for a certain amount of time, they also mentioned that if you overclock the card it will use more then 200 watt.
And including burnin with furmark now do not tell me you do not know how powerfull furmark is
Its actually more stressing cards then they will ever do in real time usage including mining

This site has allways been in this respect good they test every aspect, and i believe they did more testing then others
So there is no doubt about the results, these guys test with better equipment then a kill-a-watt

Onto the answer with the threads running in the old stucture the alu where not capable of doing more then 2 threads
the new GCN seems to make it possible to make better use of the alu's is stated by amd.
So somehow you can get the card to set every and all alu to work
Which was simply not possible on the vliw architecture
The big increase in numbers on the review (most games) shows clearly that this card easily does up to 33% better then the 6970
I think for the coders out their this card poses a real challenge to get more out of it then with previous cards.
Nevertheless we have to wait what prices it will get at, after the initial run on them because i already know many of the gamers i talked to want 1 or more of them as soon as they can