https://www.theverge.com/circuitbreaker/2018/3/30/17180042/macos-external-gpu-support-graphics-card

Last June, Apple announced that it would add support for external GPUs to macOS. And now, just under a year later, official support has arrived. With the latest update to macOS High Sierra, you’ll be able to connect a number of different graphics cards to the Mac through a Thunderbolt 3 port and use that additional power to speed up demanding processes, including games and video editing. Apple has specifically highlighted its use for VR.

This probably shouldn’t surprise anyone since it’s Apple we’re talking about here, but there are a number of limitations around what you can do with external GPUs. For one, only select models are officially supported. And, surprise, Apple is only supporting some of AMD’s Radeon cards, which it already includes in select Macs. That doesn’t strictly mean a GeForce card won’t work — people have gotten some to work while the feature was in beta — but it means you’re gambling a bit around whether it’ll continue to work.