With the release of macOS 10.13.4, Apple has officially added native support for eGPU to the OS. If you are a regular user, this is not going to mean much to you but for developers, this is a particularly big deal as it will allow them to use a more powerful GPU with their existing Macs.
eGPUs, however, come with their own set of restrictions and requirements. Firstly, not every Mac running High Sierra can take advantage of eGPUs. That’s because eGPU requires a lot of bandwidth which means that Thunderbolt 3 support is a must. Apple says that only the following Macs running High Sierra are compatible with an external GPU:
- 2016 MacBook Pro
- 2017 MacBook Pro
- 2017 5K iMac
- 2017 5K iMac Pro
If you own any of the above-mentioned Macs, you can use an external GPU with them. Just make sure to plug in the cable in the Thunderbolt 3 port. For 13-inch MacBook owners, this means using the ports on the left side of their laptop.
Official eGPU support does not mean that you can use any GPU with your Mac. Apple recommends developers and advanced users the following GPUs:
- AMD Radeon RX 570
- AMD Radeon RX 580
- Radeon Pro WX 7100
- AMD Radeon RX Vega 56
- AMD Radeon RX Vega 64
- Vega Frontier Edition Air
- Radeon Pro WX 9100
Apple primarily recommends AMD GPUs as their OpenCL performance is extremely good which would in turn benefit apps like Final Cut Pro X and other development tools on macOS. Nvidia GPUs are not officially supported, though you can always try your luck by using Nvidia’s web drivers. But then, your mileage may vary and the performance boost might not be that significant.
Developers or advanced users can use eGPUs to power high-resolution 4K or 5K displays connected to their MacBook. It should also help in development work pertaining to VR and 3D rendering since the GPUs inside most Macs is not that powerful.
However, do note that you will likely be limited by the CPU performance of your MacBook in many scenarios or hit the limitations of the maximum bandwidth offered by Thunderbolt 3. On a 13-inch MacBook Pro with a dual-core processor, you will likely run into bottleneck issues by your CPU first which would end up capping the gains offered by the external GPU. The performance gain by using an external GPU will be higher if your MacBook has a Core i7/quad-core processor.