Halo - I'm definitively NOT the guy to ask, but I was intrigued by your comments and the answers you got about vsynch.
As you stated, yes there is a check box saying that vsync is 'application controlled' where you were led to. I went to the same place, confirmed it and left it at that & went to other subjects.
But, this bug did not leave me alone, so I went back to the screen and oh surprise, in mine there was a 'slider bar' which turns on when you click the above mentioned off at the bottom.
Interesting slider, because it says 'off' on the left side and 'on' on the right.
btw, I'm very curious as to what a 1/4 off and 3/4 on position could possibly mean - it IS a slider ... but I assume further investigation may clarify that. Who knows, maybe even here - the largest treasure trove of hardware I've ever found.
For what it's worth, maybe you have the same option to try out. I'm doing it as of now. If something strange happens, I'll let you know. If not, I'll try to figure out that 'on-off' slider.
taxi