Apple said MacBook Pro notebooks released in 2016 and later, iMacs launched in 2017 and later, and iMac Pro will support some external GPUs it recommends. Apple aims to give VR creators and pros more graphics power.
The supported Macs need to have macOS High Sierra 10.13.4 installed, and be connected to one of the "proper" graphics cards:
- AMD Radeon RX 570, RX 580, and Radeon Pro WX 7100
- AMD Radeon RX Vega 56
- AMD Radeon RX Vega 64, Vega Frontier Edition Air, Radeon Pro WX 9100
- Thunderbolt 3 all-in-one eGPU products
Apple writes on its support site:
It's important to use an eGPU with a recommended graphics card and Thunderbolt 3 chassis. And if you're using a MacBook Pro, the eGPU's Thunderbolt 3 chassis needs to provide sufficient power to run the graphics card while charging the computer. Check with the maker of the chassis to find out how much power it provides, and make sure that it's enough to charge your connected Mac notebook.
eGPU support in macOS High Sierra 10.13.4 is designed to accelerate Metal, OpenGL, and OpenCL applications that benefit from a powerful eGPU. However, not all applications support eGPU acceleration.