[SOLVED]60 hz/fps bug

[SOLVED] Issue was actually due to Nvidia Inspector Multi-Display power option triggering my 1080 Ti to go into a low clockspeed because the GPU load threshold was set too high, and at 60 FPS the game was not putting a big enough load onto the GPU.

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I experience framerate drops to <20 fps at regular, predictable intervals when the game is locked to 60 FPS.  I have tested this by:

1) setting a 60 fps framerate cap in Nvidia Control panel (NVCP) without Vsync

2) Setting unlimited fps cap in NVCP but enabling Vsync in-game @ 59.95 Hz

When the framerate is higher than 60, regardless of the refresh rate, I do no experience this bug.  The game seems to cause my GPU to reduce clockspeeds, which results in the bad performance.  

Also, as the developers are aware, I experience bad visual stuttering when the game is running above 60 fps - as reported by MSI Afterburner.  The framerate will say >100, but the game looks like it's capped at 30 fps.  However, when the game doesn't drop performance and when I cap the framerate at 60, it appears much smoother between the performance drops.  You can see what happens in my Afterburner log:

The left hand part of the graph shows the game running at a 60 FPS cap.  The right hand portion of the graph has the game capped at 120 FPS.