vsynch not working In full screen

I added a script to check the FPS when I run my game. When build and Run when my game has vsync set to every vBlank. When I play my game in window mode my FPS is locked at 60 and playing the game feels very smooth as it should. However when I run the game in fullscreen at the same resolution my fps counter says Its running at 340 fps and everything seems to studder and when I do certain things in my game it drops to like 4 fps for a second and overall not a smooth experience Is this something with Unity? or maybe my graphics drivers? I have no clue really what to do about this.