this goes away when turning off shadows completely and gets worse on lower settings
Which graphic settings did you have?
Which graphic card do you have?
this happens with any of the shadows turned on with full screen and vsync disabled and everything else maxed
I have an NVIDIA GeForce GTX 960
here is my dxdiag will all the info you would want
it almost seems to be an artifact depending on what chunk of the world my camera is in as the line can move around when viewing from different locations
Paging @not_owen_wilson, this seems to be up your alley!