I did a clean install and no change. I think its Win10 17074 but just wanting others to confirm there are no issues with 10.5 or the latest NVIDIA drivers.
If anything, my generic HP/nVidia GTX1060 3GB went up 5% with 10.5 and I had recently installed Windows 10 "Winter update".
I do have a nit in that it shows my hash rate for Sia = 10× the rate for Ethereum (precisely, moves decimal one place left).
My hash rate was consistent 19.7 Mh/s before and now is sticking to 20.1