Yes you are right, the DPS-1200FB fan would explain for the 10w draw on rest. But that leaves 30w to be accounted for? My 1080 is water cooled, so no fans there. The raiser must eat a little, but a whole 30w?
Well 180 at .93 eff is really 7% higher that is about 13 watts
And maybe you have a gold not a platinum
It is easy to tell the power cord socket blue in color is platinum
The power cord socket black in color is gold
Gold is 88%. So 12% of 180 is 21.6 watts
I also don’t know what the nvidia software counts when it reads 180 watts.
But if I use smos to run a pc and set a card to 180 watts a two card rig is 400 not 360.
In your case you would be 440 that does seem a bit high.