Dell U2415 blurry text

Using 3 x U2415 screens and it seems all of them have blurry text.

Tried to adjust clear type text on windows 7 with no success.

Updated to windows 10 , same issue.

Tried with graphics card GTX960 using 3 x MiniDP ... no luck.

Switched to 2 x GTX750Ti using HDMI ... same problem.

Any ideas how to solve it will be appreciated.

Was using 2410 before and all was perfect.

Seems the U2415 is not as good and only now I found people complaining about the same problem.