MacOS Mojave lets you use an eGPU with a MacBook Pro display. And the gaming boost can be fantastic

As of the latest public beta patch for macOS Mojave, eGPU
support for the Mac is truly worth getting excited about. Back
when I
first covered Mac eGPU support
, I noted that it came with
one significant drawback: You could only see its benefits
through an external monitor. Fortunately, that’s no longer the
case. Apple now lets you accelerate graphics directly on the
display of a MacBook Pro or iMac, and even more impressively,
it lets you easily choose which apps will benefit from that
acceleration.

The general process of hooking up an eGPU hasn’t changed much.
All you need to do is have a compatible graphics card (which
will almost always be AMD, as Nvidia cards still aren’t
supported) and an eGPU enclosure to put it in. From there, you
just plug the eGPU into your Mac through the Thunderbolt 3 port
(which means this only works on Macs made within the last
couple of years). Your Mac will immediately recognize the eGPU.
There’s no need to install specific drivers or restart your
Mac. Overall, it’s a good example of the elegant simplicity we
expect from Apple.

And now Apple extends that simplicity to the rest of the
experience by easily letting you choose which apps you want to
power with your graphics card. The feature has actually been
around since macOS 10.13.4, but before it required dropping
some code in the Terminal.

In Mojave, choosing which app to accelerate is a simple matter
of finding the app through the Finder, right-clicking on the
app, choosing Get Info, and then checking the box for “Prefer
External GPU.” And presto. When you open the app, you’ll likely
see a massive leap in performance.

accelerating app with egpu
Leif Johnson/IDG

The option only shows up if the eGPU is actually connected.

Now we’re playing with power

Of course, your mileage varies depending on the card you’re
using. I conducted most of my tests with a
Razer Core X
eGPU enclosure on a 2017 15-inch MacBook Pro
with Touch Bar and 16GB of RAM. I started off with a Radeon RX
480, but the differences in performance were barely noticeable.
I initially wasn’t even sure if it was working properly.

So I decided to aim for the stars. I took the most powerful AMD
graphics card we have on hand—the water-cooled AMD Radeon RX
Vega 64—and plopped it into the Core X. (As you’ll see in the
photos, I left off the Core X’s case so I wouldn’t have to
worry about fitting in the attached cooling unit.)

The difference was breathtaking.

vega 64 egpu macbook pro
Leif Johnson/IDG

Even if the setup was not.

Using the built-in benchmarking tool for the demanding game
Rise of the Tomb Raider at 1920 by 1200 resolution on
Very High settings and Vsync disabled, I was able to achieve an
average of 62 frames per second in one section of the benchmark
and 47 and 44 fps in the two more demanding portions. The high
end reached 110 fps (although the low sometimes dipped to 11
fps). And to think, this is on the MacBook Pro’s native
display! Granted, I had it set at a resolution that’s
below its native 2880-by-1800, but with these settings the eGPU
delivers an experience that’s more in line with how the game is
supposed to look.

Now compare that to the heartbreakingly awful performance I was
getting with the MacBook Pro’s onboard discrete Radeon Pro 555
graphics card with the same settings:

macbook pro no egpu Leif Johnson/IDG

I found similar (if less impressive) results with the 2017
15-inch MacBook Pro when I used Unigine’s aging Valley
benchmarking tool. For this test, I pumped the settings up to
an “Ultra” resolution at 1920-by-1080 and was only able to
achieve a max frame rate of 61.4 with the Vega 64. Still, as
you can see, the eGPU still delivers a massive improvement,
even if it’s not as far-reaching as I would have liked. 

unigine valley IDG

Your Mac’s RAM also makes a ton of difference. I tried out the
same test on a 2017 4K iMac with 8GB of RAM at 1920 by 1080
resolution and was only able to achieve a maximum average of
42.56 fps. (Forget about running it at the full 4K: It slowed
to a crawl.) With the two more demanding tests dipped as low as
30 fps.

What’s the catch?

It’s fantastic that you can now get this kind of graphical
acceleration on the MacBook Pro’s own display, particularly if
you have older Macs that can’t quite keep up with modern
demands. But just because you can doesn’t mean you
should.

Remember how you once could only use eGPUs on a Mac through an
external monitor? As it turns out, that’s still the best way to
go.

In my case, I hooked up the eGPU to a fairly humble 24-inch
Acer PS44W display (and shut the lid off the Mac itself for
better performance), expecting minor improvements at best.
Instead, I audibly gasped. You can see why in the Rise of
the Tomb Raider
benchmarks below:

external monitor IDG

That’s … stunning (at least for a Mac). There’s a lot of
variation here, of course, but on the screen the benchmark
looked beautiful and smooth. I saw similar results with Unigine
(although, again, they weren’t as impressive).

external monitor IDG

I like to think that anyone walking by would have a hard time
believing they were seeing a MacBook Pro in action. I
personally could live without the external display as I’m
mainly interested in an eGPU for gaming convenience, but when
you’re used to the limitations of the native graphics card,
it’s hard not to be awed by these numbers.

A thousand-dollar convenience

Financial concerns aside, I can live with this. Heck, I’ll go
ahead and say I can be happy with it. As it works in
Mojave, this eGPU setup lets me take my MacBook Pro out
into the world and use it as the work-focused tool it’s meant
to be, and when I get home, I can hook up that MacBook to my
eGPU and play games with an experience that’s reasonably
similar to what you’d get on a PC. In some ways, it’s the best
of both worlds.

But real talk: This is a lot of money for just
“reasonably similar.” In both the case of the iMac and the
MacBook Pro, I had to crank down the resolution to achieve
these results on Very High settings. For “reasonably similar,”
you need to drop $299 on the Razer Core X and at least
$699 on the Vega 64. That’s another $1,000 on top of the larger
chunk of change you probably paid for your MacBook Pro, and
it’s still not going to guarantee you the holy grail of 60 fps.

Don’t forget that I was achieving these results with one of the
best graphics cards we Mac users can currently use. If you get
anything less powerful than this, the results may dip
significantly.

And for that matter, some of the old limitations still remain.
You still can’t use eGPUs through Boot Camp, which means you
can forget about using them to play PC games on Windows with
the same machine. You’re also still stuck with AMD cards, which
is quite the bummer in a desktop gaming culture that tends to
favor Nvidia cards.

razer core x nvidia Leif Johnson/IDG

And yes, we tried.

Still, I’m glad Apple is giving eGPUs more attention, and that
attention may translate into some bigger surprises when Apple
finally gets around to showing us the new Mac Pro. 

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