I purchased a new lenovo Legion y720 laptop with gtx1060 6gb. After somedays of use, i noticed heavy fps drops (10-20 fps from 60) in all games. I checked dxdiag and found that it could not identify my GPU memory, it showed N/a. So i reinstalled all nvidia stuff, then games started working fine. Now for every 2 or 3 days same thing happens and i have to reinstall all the stuff again and again. See the screenshot uploaded to see what i'm trying to say. 
Graphic card problem?
Gahaninadh
Contact Lenovo customer support for the help you already paid for or exchange that laptop.
Starrysky