How to use a Mac eGPU (external graphics processor)

Macs equipped with Thunderbolt 3 can boost graphics performance using an external graphics processor (eGPU). Here’s a rundown of how this technology works, what it’s good for, and how to get a Mac eGPU.

Over the past few years eGPUs have moved from fringe devices for bleeding-edge early adopters to mainstream peripherals that anyone can use to enhance the performance of their Mac. In this overview, we’ll break down the basics of eGPU use to give you a better understanding of what this tech means for you.

What is an eGPU?
Which Macs support eGPUs?
What eGPUs work with the Mac?
What eGPU cards work with the Mac?
How do apps work with an eGPU?
How to use the Prefer External GPU option

What is an eGPU?

An eGPU gives the Mac additional graphics performance. It’s an external box that houses a PCI Express-based graphics card. The device connects to the Mac using a Thunderbolt 3 cable. Thunderbolt 3 has the bandwidth needed to offload graphics processing to an external processor without creating delays or latency which affect on-screen performance.

eGPUs work with applications that support Apple’s Metal graphics API, as well as apps that support OpenGL and OpenCL. By installing an eGPU, you can help your Mac speed up video frame rates in demanding applications, increase the performance of rendering of complex visual effects and 3D scenes, decrease the amount of time your Mac spends exporting videos or complex image files, and even speed up performance in some games.

Which Macs support eGPUs?

Any Mac equipped with a Thunderbolt 3 port, running macOS 10.13.4 or later, can support an eGPU. Which ones it actually makes sense to use will depend on a few factors, including your specific needs and your budget. With prices starting as low as $250, there’s an eGPU rig in almost everyone’s budget.

If you’re working with a Mac laptop with limited graphics horsepower, such as a MacBook Air or a 13-inch MacBook Pro, an eGPU can provide with you with much more powerful graphics processing capabilities than you’d be able to otherwise manage. An eGPU chassis gives you a way of hooking up powerful graphics support when you need it, while maintaining lightweight portability when you don’t.

This also makes an eGPU chassis suitable for the Mac mini, which also comes with limited integrated graphics processors. But eGPUs work with any Mac that includes Thunderbolt 3 – so if you’re looking to give your iMac Pro or your 16-inch MacBook Pro a big shot in the arm for graphics performance, it’s worth a look.

What eGPUs work on the Mac?

An eGPU chassis equipped with Thunderbolt 3 ports will work on the Mac. Apple maintains a list in a support document on its web site. eGPUs mentioned on Apple’s site include:

Different makers emphasize different features. Most include additional display support either using HDMI or DisplayPort interfaces, USB ports for additional peripheral connectivity, and other capabilities. There are a couple of things to look out for when shopping for a Mac eGPU. If you’re planning to work with a Mac laptop, for example, you want to make sure that the eGPU provides sufficient power to run both the graphics card and charge the Mac.

How much power you’re going to need will depend on which model of Mac laptop you’re using. As long as the eGPU chassis can provide up to 100W of power for a connected computer, you’ll be covered regardless of which Mac laptop you connect.

Some vendors sell eGPU chassis bare, so you can use your own graphics card. Others will install one so you’re all set and ready to go once it arrives. Just make sure the card will work with the Mac. That brings us to our next topic.

What eGPU cards work with the Mac?

One important thing to know when you’re shopping for a Mac eGPU – you’ll see a lot of sites hawking eGPUs populated with Nvidia cards. Unfortunately, they’re not a good choice for the Mac. Apple explains:

The GPU drivers delivered with macOS are also designed to enable a high quality, high performance experience when using an eGPU, as described in the list of recommended eGPU chassis and graphics card configurations below. Because of this deep system integration, only graphics cards that use the same GPU architecture as those built into Mac products are supported in macOS.

While Nvidia-based graphics cards are broadly popular on the Windows platform, Apple is much more closely aligned with Nvidia rival AMD. The eGPU configurations Apple recommends all support AMD Radeon graphics cards.

The good news is that you don’t need a specialty card made expressly for eGPUs. You just need one with macOS eGPU driver support. Any commodity Windows graphics card that uses these AMD chip architectures should work, according to Apple:

AMD Polaris architecture, including Radeon RX 470, RX 480, RX 570, RX 580, and Radeon Pro WX 7100
AMD Vega 56 architecture, including Radeon RX Vega 56
AMD Vega 64 architecture, including Radeon RX Vega 64, Vega Frontier Edition Air, and Radeon Pro WX 9100
AMD Navi RDNA architecture, including Radeon RX 5700, 5700 XT, and 5700 XT 50th Anniversary. Apple notes that support for these cards requires macOS Catalina 10.15.1 or later.

How do apps work with an eGPU?

Apple bakes its own eGPU driver support into macOS, and has since macOS 10.13.4. Apple’s eGPU drivers can accelerate apps that support Apple’s Metal Application Programming Interface (API), OpenGL, and OpenCL as well.

eGPU support varies from app to app, so it’s wisest to check with the makers of the apps you depend on before assuming an eGPU will work. But an increasing number of apps for creative professionals, gamers, architects, scientists and engineers benefit from eGPU support.

Some apps will require that you use a display connected directly to the eGPU to accelerate. Others will optionally accelerate on an eGPU while still using the built-in display. This is thanks to a new Finder option available in macOS 10.14 or later: Prefer External GPU.

How to use the Prefer External GPU option

With macOS 10.14 and later, Apple has made it possible for apps to offload graphics procesIf your app supports the Prefer External GPU option, here’s how it works:

1) Make sure your Mac is running macOS 10.14 or later.

2) Select the app in the Finder.

3) Press Command and I to show the app’s info window.

4) If the apps supports the preference, you will see a Prefer External GPU option. Click the checkbox to set.

This checkbox will not be visible if your eGPU is disconnected, if you’re running macOS 10.13, or if the app manages its GPU selection itself.

Wrapping up

By now you should have a clear idea of how eGPUs work on the Mac and what you’ll need to get started. Are you going to get an eGPU for your Mac? If so, which one? Or are you already using one? Tell me how you’re doing in the comments, and fire away with any questions, too!