Disable USB C Alt Mode?

Hi,

I can't get video out from USB C to stop flickering. It's a mess. But the only way I can get Chroma other USB passthrough functions to work on my Raptor 27 is if it's connected via USB C.

So, I have it connected via HDMI - there's no flickering. But the laptop also still displays video signal through the USB C Alt Mode. I imagine this is unnecessarily using the CPU. How do I turn off AltMode so that I can still retain the USB hub functionality?