Assuming Zwift is using the Nvidia GPU and not integrated graphics from your Intel CPU, then my first guess is it’s this problem, you were screwed by a Microsoft update, and removing one or more updates is the workaround:
If you upload logs to trainerdx.com that would reveal which GPU is being used but if the cable is plugged into your GTX 745 then there’s nothing else we need to know.
Your system is supported by Zwift and should be stable if everything else is working OK. Upgrading to a GPU like an Nvidia GTX 1050 Ti should also get you out of range of that problem.
BTW I would not call that a potato. The bar is low.