Do you really need an eGPU with a 2018 Mac Mini?

We combined a Vega 56 full-sized video card with a 2018 Mac mini using the OWC Mercury Helios FX Thunderbolt 3 enclosure. Read on to find out if this is a winning combination.
Written by David Gewirtz, Senior Contributing Editor

A fully-equipped 2018 Mac Mini is impressive in all but one way. Its graphics capabilities are anemic.

Fortunately, it doesn't have to stay that way. All currently-shipping modern Macs (we won't talk about the trash can!) support Thunderbolt 3. That means that all modern Macs, from the lowliest 2018 MacBook Air to the Mac Mini, can be turbocharged with a high-end graphics card in an eGPU (external GPU) case.

When I built out my 2018 Mac Mini with the intent of making it my main workhorse machine, I knew its onboard Intel 630 graphics were probably not good enough for the kind of graphics load multicam 4K video editing requires. I was right.

I'm not going to give you benchmarks, because they can be found all over the web. But I will tell you this: The off-the-shelf Mac Mini i7 with 32GB of RAM edited a single 4K video stream in Final Cut surprisingly well. But add a second camera and everything slowed to a crawl. Toss some effects on top of that stream, add a third or fourth 4K video layer, and the chipboard 630 chip didn't have the chops.

For that kind of load, an eGPU was necessary. I've reviewed a number of OWC products in the past with excellent results, so I reached out to it for its Mercury Helios FX eGPU enclosure. To that, I added the Sapphire Vega 56 card recommended directly by Apple. The exact model I bought was the Sapphire Radeon Pulse RX Vega 56 8GB HBM2 Dual HDMI/DP PCI-E Graphics Card.

At $579, the card was a quarter of the cost of the whole Mac Mini, but I expected the expense when I planned the purchase. It's still a whole lot less expensive than a MacBook Pro or iMac, both with screens I didn't want.

If you add the $299 price of the Helios FX enclosure to the $579 GPU, the total eGPU solution cost is $879.

Also: Max out your new Mac Mini with iFixit's new RAM upgrade kit

Now, compare that to Apple's recommended BlackMagic eGPU Pro, which sells for $1,199. It also contains an 8GB Vega 56, but it adds a bunch of ports, turning it into a Thunderbolt hub. While the extra $320 might be worth it for the extra ports, the big ding against Apple's eGPU solution is that it's not upgradeable.

The downside of this is all too clear. In June, Apple announced the BlackMagic eGPU, containing a Radeon Pro 580 GPU. Had you bought that for $699, you would have been out of luck in October, just four months later, when Apple introduced the eGPU Pro. There's no upgrade path between the two units.

By contrast, I can sell my Vega 56 at any time. It's a standard PC board, and given how many crypto miners are buying up GPUs, there's always a used board market. Even if I upgrade after a year or two of use, I can probably get close to half my board cost back. I'd simply be able to buy the next generation and drop it into the Helios FX enclosure.

This is the OWC Mercury Helios FX eGPU case.

The Helios FX enclosure

The only limit on the Helios FX enclosure is that it won't fit the Vega 64 cards. Those are bigger, and the Helios isn't huge. But since even Apple's Pro eGPU doesn't support the Vega 64, I don't feel like I'm missing anything.

As for the Helios FX enclosure, there's not much to say. It just works. It's basically a small form factor PC case. The skin unscrews with three thumb screws at the back and lifts out and up. If you've built a PC, you've seen this kind of case.

Also: Yes, it's possible to upgrade a 2018 Mac Mini's RAM. No, it's not easy

All you do is drop the GPU card into the slot, plug in the power connectors, and close it back up. I routed my Thunderbolt 3 cable from the Mac Mini to the Helios FX and then a DisplayPort cable to my 38-inch (yay! finally!) monitor.

There is no doubt the enclosure is a bit of a beast. I have my Mac Mini sitting on top of it. But so far, I haven't noticed any noise coming from it, and I've produced a bunch of video. It's sounding like both the Mac Mini and the Helios enclosure are actually pretty silent.

eGPU and display performance

Although my old 2013 iMac was as fully-equipped as it was possible to do back in 2013, it was huffing and puffing a bit doing multicam 4K video. While I definitely needed the performance improvement, what I really wanted was one of the ultrawide displays. That old iMac wouldn't support the resolution for an ultrawide.

Get Info tells Compressor to prefer the external GPU when possible.

The 2018 Mac Mini supports ultrawide monitors, even without the eGPU and the Helios enclosure. The eGPU and the Mac Mini make a powerful combination and I'm loving the ultrawide display.

I've been curious about eGPU performance, especially about when the eGPU kicks in and out. I kind of think of it like an afterburner. It turbo-boosts some video processing, but not everything. There's an option in the Get Info tab of most apps that allows you to specify Prefer External GPU. So far, I've found most apps default to the eGPU if it's available. Most apps... except Compressor.

Also: Yes, I bought a 2018 Mac Mini (and here's how I spec'd it out)

Compressor is the encoding program that takes video edited in Final Cut and turns it into a file for viewing or uploading. Oddly enough, when I started to run Compressor, the eGPU stopped doing its thing and all the processing moved to the Intel 630.

Compressor used the internal GPU (the lower graph)

I was actually convinced something was wrong with the Helios or the eGPU itself. There's even a Use GPU option inside of Compressor, which I definitely made sure to check. Still, it processed on the 630 chip.

I contacted tech support, I called around to friends who use Final Cut. Finally, I got an answer on one of the Facebook Final Cut boards. Apparently, Compressor uses an encoding feature built into the Intel chipset. So, as much as I would have expected the eGPU to do the heavy encoding, it's actually on the main board. Go figure.

I have had the opportunity to use both the eGPU and on-board 630 chip together. Check out this graph from when I was exporting a bunch of images and 4K video from Photos (using the eGPU) and running Compressor (using the 630 chip).

Must read


Let's use all that power!

Bottom line

Can you edit Final Cut Pro X 4K video with just the Mac Mini? Yes. With a single video source, it's not bad. But once you add more video sources, multicam, and effects, it gets painful. Adding on the eGPU makes it very nice, indeed.

I'm a bit weirded about why Compressor insists on using the on-board video, but that's neither the fault of the Vega 56 nor the Mercury Helios FX. That's just Apple being Apple.

Also: New 2018 Mac Mini: Pro machine in a tiny, upgradeable package

The real bottom line is I am thrilled with Thunderbolt 3, the 2018 Mac Mini, and the ability to add a full-sized high-end PC GPU to my setup. The Mercury Helios FX was standout in how quickly it faded into the background and just did its job.

All told, if you're doing extreme pro work, the 2018 i7 Mac Mini, the Vega 56, and the Helios FX can help you get your job done -- and all together, at about two-thirds of the entry price of a base iMac Pro.

You can follow my day-to-day project updates on social media. Be sure to follow me on Twitter at @DavidGewirtz, on Facebook at Facebook.com/DavidGewirtz, on Instagram at Instagram.com/DavidGewirtz, and on YouTube at YouTube.com/DavidGewirtzTVAffiliate disclosure: ZDNet earns commission from the products and services featured on this page.

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