Are you sure about that? I can imagine that C1060 and GTX280 and such numbers are not including these kinds of losses, but for S1070, NVIDIA has control over the PSU, so I would imagine these number to be accurate.
The S1070 uses C1060’s which are rated for 200W. S1070’s 800W figure seems just a simple multiply of that. Actually, notice that the S1070’s 800W is actually “typical power consumption.” Sorry, I didn’t see that at first.
To answer the OP: However, I don’t think the S1070’s “typical” is comparable to the S870’s “typical.” (S870 gave an optimistic figure and a pessimistic one, S1070 just something in the middle.) I think overall power consumption is up no more than 20%, not 50%.