To unlock frame rate open Fallout4Pref.ini
That is located at C:\Users\yourname\Documents\My Games\Fallout4\.
Search for iPresentInterval=1, and change it to iPresentInterval=0
Search for bForceIgnoreSmoothness=0 and change it to bForceIgnoreSmoothness=1

Next go to nvidia control panel (right click on the desktop)
Now go to Manage 3D settings and Program settings. There you add Fallout 4 and use settings i put bellow.

Use these settings, everything else default.
Triple Buffer on.
Max frames render ahead to 1.
V-Sync on.