toxa (тоха??), i have resolved this issue by installing 16.5.1.2 (or 16.1.5.2) driver. There was a note from one staff on lenovo forum. Somehow, 16.1.5.2 works perfectly on Lenovo t440s, while 16.6 is not working well.
Also on russian forum ixbt, someone said that 16.8 is good for N-7260. You can download 16.8 from dell site or google it. Intel didn't ,ake official release of 16.8