When using borderless mining, the refresh rate of my monitor is automatically set to 60hz. I have tried adjusting fullscreen resolution to 144hz in the sodium menu, but since borderless mining overrides that it doesn't change anything.

Possible that I'm just missing an obvious solution though.

What's your desktop refresh rate set to in your system's settings? Are you using a custom resolution configured in the driver?

Closing: insufficient information to replicate; possibly a duplicate of #26