Will it cut it?
The new 680SLI review shows 549 Watts is the maximum power draw. The 2600k was OCed to 4.8GHz. At 80% effeciency you would need around 650-700 Watt PSU for SLI 680's.
We tested the power utilization at the wall
You reversed the math here. From the review:
The power draw from the review is AT THE WALL AC.
The RATED POWER from a PSU is internal DC.
If you assume %80 efficiency the true DC power draw of the [H] test system is ROUGHLY 550w * (80/100) = 440w.
Of course this is assuming the measurement device they used is accurate (NEVER to be assumed when measuring AC Power), but even if it's off by 50-100w there's still enough juice from a 750w PSU. Even if the AC wall measurements are way off (say 650w-700w real-world AC consumption) this leaves you a little room for video overclocking.
No I meant that most good PSU's are 80% efficient. I did not see that they measured at the wall, which I should of known since [H] has measured at the wall for a long time (just picked up my own Kill-A-Watt )He might have been saying that you don't want to be pushing your psu at a constant 80-90%+ max rated capacity, so provisioned the psu to that end. Although that still leaves what you pointed out as to the draw on the psu itself being lower than 550W, so it in some ways compensates.