Apple iMac Pro review: Iron fist in a velvet glove

Workstations. Not a category of product one would typically associate with the word “gorgeous”. Or “beautiful”. Or “stunning”. And yet all three trip off the tongue in the Apple iMac Pro word-association game.

To be fair, the same could be said of any iMac Apple has produced in the past few years – and there’s very little difference, from a physical perspective at least, between the iMac Pro and the 27in 5K iMac launched four years ago. But it’s easy to understand why Apple has stuck with the tried and tested here.

READ NEXT: Apple Mac Pro (late 2013) review

The simple fact is that the iMac Pro doesn’t need a redesign. It remains the very model of cool sophistication and minimalism. Its clean lines, smoothly curved rear and low-profile Magic Mouse and keyboard look fabulous on any desk, especially desks favoured by Bauhaus designers with rimless glasses.

[gallery:3]

So what separates the iMac Pro from its far cheaper siblings – aside from the rather fetching Space Grey finish, matching moody peripherals and shock-treatment price? There are a couple of small improvements, including the ability to VESA mount the iMac Pro to a stand of your choice and a collection of new connections at the rear, but really it’s all about what’s inside.

And what’s inside the iMac is drastically different from what you’d find in a regular iMac 27in, even the top-line 5K model. Instead of Intel’s consumer-focused Core CPUs, you have a choice of Intel Xeon W processors. You know, the sort of thing you get in proper workstations like this one from HP or this one from Dell.

Buried deep in the heart of the model I have to review is a workstation-grade 3.2GHz eight-core, 16-thread Xeon W-2140B processor, but you can upgrade that to a 3GHz ten-core, a 2.5GHz 14-core or a 4.3GHz 18-core chip if you want more processing grunt and future-proofing.

[gallery:2]

As for RAM, well, this machine has a mere 32GB of 2,666MHz DDR4 ECC but again you can up that to 64GB or 128GB if you like. The storage subsystem is equally impressive, with the 1TB SSD upgradable at the point of purchase to 2TB or 4TB of SSD storage. Plus, there’s a choice of AMD Radeon Pro Vega 56 or Vega 64 graphics, the former with 8GB of HBM2 memory, the latter with 16GB.

For context, the model I’ve been testing for this review is the cheapest Apple makes and that even that costs a hefty £4,899. If you want the 2.3GHz 18-core machine with 128GB of RAM, a 4TB SSD and a Radeon Pro Vega 64 – and, let’s face it, who wouldn’t? – it will set you back £12,279.

Apple iMac Pro models

Apple’s “recommended configurations”
3.2GHz 8-core Intel Xeon W; 32GB RAM; 1TB SSD; 8GB Radeon Pro Vega 56	£4,899
3GHz 10-core Intel Xeon W; 64GB RAM; 2TB SSD; 16GB Radeon Pro Vega 64	£7,599
3GHz 10-core Intel Xeon W; 128GB RAM; 2TB SSD; 16GB Radeon Pro Vega 64	£9,039
Top specification
2.3GHz 18-core Intel Xeon W; 128GB RAM; 4TB SSD; 16GB Radeon Pro Vega 64	£12,279
Processor upgrades and cost (base spec: 3.2GHz 8-core Intel Xeon W)
3GHz 10-core Intel Xeon W	+£720
2.5GHz 14-core Intel Xeon W	+£1,440
2.3GHz 18-core Intel Xeon W	+£2,160
RAM upgrades and cost (base spec: 32GB)
64GB 2,666GHz DDR4 ECC	+£720
128GB 2,666GHz DDR4 ECC	+£2,160
Storage (base spec: 1TB SSD)
2TB SSD	+£720
4TB SSD	+£2,520

Apple iMac Pro review: Performance

In all its guises, though, the iMac Pro is a ludicrously powerful machine. It’s intended to deal with power-hungry tasks such as 4K and 8K video editing and rendering, complex music creation and mixing, CAD/CAM, 3D visualisation and design, even VR-driven design work – the sorts of thing car manufacturers like McClaren are starting to do with their car chassis design. These are the types of job that bring even the most powerful of consumer systems to their knees.

You probably won’t need an iMac Pro if you’re simply editing basic 1080p clips or putting together straightforward 4K video-editing projects. Nor is this the machine for photo editing or illustration – you’d have to be working on files with hundreds of layers and filters for it to be worth the extra outlay. 

But if your video projects are long and complex, you’re working with multiple layer effects, or you deal with complex 3D models on a regular basis, the extra power will certainly come in handy, as will the iMac Pro’s ECC RAM, which should make it slightly less likely to crash – handy if you’re going to be using the machine for long renders. And, as Apple was keen to point out, creative professionals are increasingly having to work on 360-degree video and VR content, which places a huge strain on computer hardware.

So, how does it perform? That will depend largely on the sorts of tasks you put it to, but in our suite of benchmarks, the iMac Pro puts clear water between itself and the regular 5K iMac.

Our in-house benchmarks carry out a series of demanding image- and video-conversion tests and finishes off these basic tasks with a multitasking test that runs these in parallel and plays back a 4K video file at the same time. An overall score of 281 makes it more than twice as fast as the 27in iMac 5K we’ve tested, which is only what you’d expect from a machine that’s more than double the price.

I also ran a series of workstation-centric benchmarks on the iMac Pro in an attempt to push it even harder, including Cinebench and a down-conversion of a 4K movie file to 1080p – the sort of process users of the iMac Pro would be likely to have to do on a fairly regular basis – and none of these threw up any issues.

Compared with a selection of similarly equipped desktop workstations tested recently by our sister title PC Pro, the iMac Pro I have on test here stacks up competitively, and it’s also worth pointing out that throughout the testing, the iMac Pro remained responsive, quiet and thermally stable.

[gallery:6]

Take the 4K down conversion. Using Adobe Premiere’s High Quality 1080p preset, the iMac Pro completed this with OpenCL hardware acceleration enabled in 6mins 45secs and with Metal hardware acceleration in 6mins 40secs. That’s not quite as quick as the £2,500 big-box workstations from that test, but bear in mind those were equipped with cheaper Intel Core i9 processors, so it’s not far behind.

In the Luxmark Hotel Lobby GPU test, it fared better, beating all but the super-expensive £4,650 plus machines with a score of 3,577 and in Cinebench 15 a CPU score of 1680 places it mid-table once again.

The iMac Pro’s stellar performance continues through to storage and here speed is more competitive. The 1TB NVMe SSD storage allocation inside the iMac Pro is an impressive beast. In fact, it’s made up of two drives in a sort-of-RAID configuration and it kicks out some impressive numbers. Sequential write speeds reached 3,003MB/sec and sequential reads of 2,487MB/sec in the BlackMagic disk test. This is around three times as fast as the 512GB drive in the Mac Pro I reviewed way back in 2014, which is still no slouch.

[gallery:7]

What’s more, it achieves this with full AES disk encryption in place – hardware accelerated by the iMac Pro’s new Apple T2 security chip. Not everyone needs such a high level of security, of course, but for those that do, it’s good to see that its application doesn’t have a negative impact on performance.

Graphics performance doesn’t quite reveal the same advantage. Tested using Unigine’s Heaven benchmark, the iMac Pro reached 48fps at 2,560 x 1,440 resolution and medium detail, which is only a slight improvement over the 5K iMac’s result. It is, however, still impressive and it’s worth remembering that, if you do need more graphical grunt – for GPGPU acceleration for instance – you’ll shortly be able to hook up external graphics cards via one of the iMac Pro’s Thunderbolt 3 ports.

READ NEXT: Apple Mac Pro (late 2013) review

Apple iMac Pro review: Display

The Thunderbolt 3 connections on the rear of the iMac Pro can be used to hook up two extra 5K displays in addition to the 27in display already in place.

But you’re not going to buy an iMac Pro for its display connectivity. If that’s all you want, you’re better off buying a workstation PC in a big, boring box from the likes of Dell, HP, Scan or Armari. You’ll receive a similar level of specification for much less than this, and can then specify a monitor of your choice. Bear in mind that if you want a monitor that matches the iMac Pro’s for quality, though, you’re looking at total spend that’s not far off that of the equivalent iMac Pro.

The difference is, of course, that you don’t have to buy the monitor again if you want to upgrade your processor, graphics card or any other component. Beautiful though the iMac Pro is, practical and easy to upgrade it ain’t.

[gallery:1]

But, as I’ve come to expect over the years, the screen attached to the iMac Pro is an absolute corker. Out of the box, the iMac’s 5K IPS panel comes tuned to the DCI-P3 colour space and, when I tested it with our in-house colorimeter, it was absolutely spot on, reproducing 98.9% of the DCI-P3 colour space. Brightness and contrast are excellent, too, reaching a searing 551cd/m2 and a contrast ratio of 1,044:1.

The only complaint you could possibly have about the iMac Pro’s display is the rather broad bezel. In a world where smartphone, laptop and tablet manufacturers are falling over themselves to fill the fronts of their devices with nothing but screen, this is the only area where the iMac Pro looks behind the times.

The gloss finish isn’t ideal either if you work in an office with overhead strip-lighting, although in the time I was using the machine, the iMac Pro’s anti-reflective coating did a good job of keeping distractions to a minimum.

READ NEXT: Apple Mac Pro (late 2013) review

Apple iMac Pro review: Verdict

There’s no question that Apple’s iMac Pro is a hugely impressive machine. Its processing power, storage subsystem and connectivity are fantastic and it isn’t even badly overpriced when you take into account that it’s all attached to a professional-grade DCI-P3 calibrated 27in 5K monitor.

Of course, you do get more bang for your buck if you go with separates, especially as you bump up the specifications for the iMac Pro, tempting though it might be. That was always going to be the case.

However, as an elegant, powerful all-in-one for the modern digital creative who’s pushed for space, there’s nothing else like the Apple iMac Pro on the market. It’s powerful, practical, flexible and capable. The most powerful iMac Apple has ever made is also the best all-in-one ever made.