I was looking at donating my current PSU in my P183 the Corsair HX 620w to another PC with a failing power supply so was researching this model even though 850W is complete and total overkill.
The efficiency numbers on page 5 are way off.
If you look at the numbers and think about it - more likely to be a few typo's in there don't you think?
Using your figures for efficiency gives a very unlikely shaped curve for efficiency vs. power.
I think what's happened is the values for AC input from 355 to 878 should move down one place, the value of 885 is spurious and there is a value missing between 234 and 355!
That gives the right answers.