It's obviously my Asus monitor that adds it as it disappears when I click the GamePlus button and select FPS Counter, but it always returns when I exits the menu (time-out or exit button). It shows always, no matter if I'm in-game or not. It is NOT the GeForce Experience counter as I have turned this on, and placed it thew same place, and it only shows in-game. It came when I turned the max FPS to 120Hz somewhere, I can't remember which program I used, and I can't find it.
I reset the monitor, and it disappeared, but it would be great to know where and how I turn it off, in case it gets back.