Quoting myself because sometime overnight the hashrate once again dropped down to the 1170 range, so adding the "-c 4" switch and setting intensity to 5 (-i 5) weren't the solution. If no one else is seeing this behavior then it must be a quirk of my system - Windows 7 Pro / SP1, 16GB RAM, AMD Phenom II x4 955 CPU, 1x GTX 1080 (for now - a second is one the way).
set swap file for 64-80g ... 6x1070ti eats 40+GB of memory
Only 1 GTX 1080 on this machine which has 16GB of system memory, so I don't need a paging/swap file at all, really. I will be adding 1 more GTC 1080 to it sometime next week - and then I might need a swap file - but I already set the swap file to 16GB minimum, 24GB maximum on the recommendation of dragonmike earlier (I honestly would have forgotten to do that had he not mentioned it, even though I did remember to manually set the swap file on my 6x 1060 Onda mining rig).