I believe i'm having issues with drivers. I'm using Windows 10, and have my MSI GTX 1070 Gaming X OC'd to 2025 Mhz Core Clock and Memory Clock to 4399 MHz. My current PPD always fluctuates, and I did have that same usage problem you have. My fix was opening up the folding viewer, and that will make it use your gpu boost. I'm assuming that drivers are still a little weird on that one. Currently i'm only getting 578k estimated PPD reported on the client. I have seen my PPD go up to 680k, that was with a different driver (I think I need to find it x.x) O.C'd to 1932 Mhz I believe, and without using the flags. I suppose I just need to do a lot more testing. Anyways, I was curious what drivers you've tested and have had luck on.
Mobo : Crosshair Hero IV : AMD Ryzen 7 1800X
Ram : G.SKILL Ripjaws V Series 16GB (2 x 8GB) GPU : MSI GTX 1070 GAMING X || EVGA GTX 1080 Hybrid
Cool : Corsair H100i PSU : Rosewill PHOTON Series 850W Full Modular