Why does FAST sync ruin your framerate

[Turtle Rig]

Ok so I choose Fast under vsync in nvpanel.  The game runs great but of course 60hz monitor but run great at 1440p all settings ultra and all nvpanel settings on or set to max...  I get 120fps no matter what AAA title I try.  Finally the chaps here helped me and we put it on vsync off,, then eventually to let card handle it,, and turn off vsync in the game.  My FPS goes to 120 if I choose Fast which basically does not tear and is very smooth.  not vsync smooth at 144hz but smooth enough for now until June when the monitor comes out..

[NineEyeRon]

Please see your other thread, posting twice in quick succession on the same subject does not help.