Sorry, but 950mv is not doing 80-83w. I'm assuming you're looking at HWinfo or GPU-z which are not complete, and/or you're forgetting to add in your idle (15w) which still would be too low.
Including idle, at the wall, i see 105-110 @ 850-860mv (1200-1265h/r depending on mem type)
Yeah, you should add about 20-25% to the numbers you're getting in HWinfo.
There's also the PSU quality to consider, you should strive to get as close to 50% PSU as you can where the efficiency is at max.
There can be quite a difference if you're using Gold or a Titanium PSU.