Okay so here is a video of my problem.
It's driving me crazy. Happens on the newest Beta drivers. Latest non-beta seems to work some of the time but I get other weird boxes and artifacts.
It reports 60fps, but feels like 30. (It doesn't fluctuate either, just feels like a flat 30fps the whole time)
I also tried messing with the flip queue size (aka max pre-rendered frames)
Does this in every game.