lmao, that isn't what the efficiency rating means
but by the by, as yes you can actually run most power supplies slightly past their rated maximum without any problems
From what I can remember the 80+ rating for efficiency basically tells you how much load you can put on a PSU while it remaining efficient and not creating any waste power which obviously turns into heat.
So for example a 1000w 80+ PSU can draw 1000w from the wall and deliver 800w actual.
So my point was that basically with these new PSUs that are 95% or what not you can draw 1000w from the wall and get 950w efficiently to the parts themselves.
Meaning that basically loading up a 850w with a 700w draw would be more than safe, and, won't start running very hot or guzzling waste power.
I will buy myself a power meter pretty soon and run some load tests on my PC with Prime 95 and Furmark. Any one know the name of a decent power meter?