Let’s face it. Just like when the iPhone 5 dropped, you lust after the iMac Pro because it is Space Grey. That phone was a substantial but reasonable upgrade - the same cannot be said for the iMac Pro.

This is a phenomenally powerful machine, one that far outstrips the needs of all but a select few users. It is the first Apple ‘Pro’ product that really will only be purchased by professionals with the need for its high-end internals.

Available with an already-insane eight cores up to an almost incomprehensible 18, this is the Mac upgrade the professional world has been clamouring for - except we probably all though it’d be in the form of a new Mac Pro, expected this year.

Instead, a brand new Apple product line is born in the iMac Pro. But do you have five grand spare?

Price and availability

The iMac costs from £4,899 in the UK. This price gets you the base model with a configurable 32GB RAM, 1TB storage and the 8-core Intel Xeon W processor. In the US, prices start at $4,999.

Apple allows you to configure at point of purchase, and the fully specced-out iMac Pro will set you back a touch over £13,000. Yes, we put the comma in the right place.

As you have already balked at, this is a lot. We don’t normally review such expensive computers but, you know, it’s Apple and this is an important product in its history.

The model we had for review was the £9,188 version, with 3GHz 10-core Xeon processor, 2TB storage, 128GB RAM and Radeon Pro Vega 64 graphics with 16GB memory plus the Magic Mouse 2 and Magic Trackpad 2 in that alluring Space Grey.

As we will explore, this is overkill for all but the top tier of Apple’s intended user base.

Design and build

The striking look of the iMac Pro is enough to turn heads. In Apple Stores the world over, staff will be asked “why is that one grey?”, inevitably leading to gasps when the price is mentioned.

But it is a thing of beauty, despite being dimensionally identical to the most recent regular 27in iMac. It’s not a stretch to paint something darker, but the iMac Pro looks awesome in its new hue, and that familiar Apple exclusivity thing boils up inside you when you first lock eyes on it.

The unit itself is a self-contained powerhouse, with all 10 cores of our review unit sitting pretty in the convex casing, interrupted on the back only for the power cable connection and the ports.

The still-magnificent curved stand holds everything reliably in place while also making it incredibly easy to adjust the angle of the screen. The bezels around the screen have not shrunk at all, but this is less important on a desktop computer than on a phone or tablet.

The unit hides its speakers well on the back too, housed as they usually are towards the bottom behind long slits.

At 9.7kg it’s a heavy machine but the fact all that computing power is in one movable unit without a tower is still incredible, and it’s easy enough to move it to a different room should you need to.

The Magic Keyboard and Magic Mouse 2 in the box are the same as you’d get with the latest iMac. The former has lower key travel than is traditional but gives a speedy typing experience nonetheless. The Magic Mouse 2 is due a redesign, but many pro users (and even lighter users) might want to opt for the precision and control afforded by Logitech’s MX Master 2S.

The Magic Trackpad 2 is also a new subtle shade of grey, and is superb to use given the whole pad employs Force Touch haptics like on newer MacBook trackpads rather than physical clicks. It might not be a full mouse replacement for some, but we found ourselves drawn to it to navigate the lush 27in monitor more often than expected.

You shouldn’t buy the iMac Pro just because you like the colour - but it’s a nice-to-have if you really do need the specs and the computer feels cutting edge despite the not-new design.

(But, nerds, you do get a black Lightning cable that you can’t buy separately anywhere. It’s cool.)

Specs and features

Where to begin? The iMac Pro is highly configurable and it gets complicated quite quickly. Regular iMacs can have four cores which is already a lot; on the iMac Pro you have the option of eight, 10, 14 or 18. Unless you’re a seasoned pro rendering graphics or video, you’re unlikely to know which to opt for just by looking at the spec sheet.

Processor

The base iMac Pro comes with a 3.2GHz 8-core Intel Xeon W processor, which can extend via Turbo Boost up to 4.2GHz. These Xeon W (the W is for workstation) processors should be your preferred choice over an iMac with a Core i5 or i7 if you run a lot of multi-threaded applications, the prime example of which being Adobe Photoshop.

This lowest tier model pushes £5,000 and will be sufficient if you want to splash on an iMac that will last you a solid few years - apart from the RAM, which itself is not user upgradable, the iMac Pro is not upgradeable at all so proceed with caution.

The advantage of buying more cores is not a matter of pure power. For example, the 10-core iMac Pro we tested actually has a lower base speed than the 8-core, but when fewer cores are needed for certain processes, it can then kick in and move up to a higher top speed.

You can see below that the 14- and 18-core models have lower base speeds than those with fewer cores, but are capable of more processing power when rendering tasks that don’t require them all.

8-core iMac Pro: runs at 3.2GHz; can reach 4.2GHz (base)

10-core iMac Pro: runs at 3.0GHz; can reach 4.5GHz (+£720)

14-core iMac Pro: runs at 2.5GHz; can reach 4.3 GHz (+£1,440)

18-core iMac Pro: runs at 2.3GHz; can reach 4.3GHz (+£2,160)

The 14- and 18-core versions can provide 28- and 36 threads of execution respectively to serve pros with the most demanding day-to-day tasks.

That’s a whole lot of oomph whichever one you go for, and Apple has ensured that only our strenuous benchmarks and top level multithreaded app work will cause the fans to start a-whirring.

This is because Apple has added a better thermal design to the iMac Pro with a dual fan system that offers 75 percent more airflow, resulting in a silent assassin of a workstation, lest you make it sweat (which, hopefully, you will).

RAM

If you go for the iMac Pro, you gain ECC RAM over the standard RAM you’ll find in the rest of the iMac line. ECC (error-correcting code) offers better reliability when tackling longer renders and intense computing processes. This is only available with Xeon W chips and Intel’s standard Core i9 processors.

The base model comes with 32GB of ECC RAM as standard but you can up this to 64- or 128GB. Pick carefully at purchase though, as while the RAM is the only component that you can upgrade on the iMac Pro after purchase, you will still have to do it via an Apple service provider.

It does have a reasonable impact on the price, though with the upgrades costing £720 or a whopping £2,160 on top of the base price.

Storage

Your storage options are, mercifully, less complex. A standard 1TB SSD can be upped to 2- or 4TB, but at an eye watering £720 or £2,520 respectively.

Many of the upgrade options on the iMac Pro will damage a bank account somewhat, but in comparison to the regular consumer market, this price increase in particular is galling; 4TB SSDs can cost half what Apple charges here.

Note that this is actually either two 512GB, 1- or 2TB flash drives paired together for 1-, 2- or 4TB configurations. Apple does this to allow for the faster I/O afforded by having two separate drives, even though they appear to the system as one.

Our advice is to stick to the 1TB base option, and spend the saved money on a Thunderbolt 3 external SSD or hard drive. It’s cheaper, you can switch between machines easier and even maybe use it on your eventual next workstation purchase.

Graphics

Apple has gone with AMD components for the two graphics options you get with the iMac Pro. The base Radeon Pro Vega 56 comes with 8GB memory, or you can upgrade to the Radeon Pro Vega 64 with 16GB memory. The decision to go with HBM memory as opposed to VRAM is a smart move as it allows for quicker throughput.

If you are at the highest end of your professional realm, you may even need to plug in an external graphics card over Thunderbolt 3. Insanity it may seem, but even the iMac Pro can't cope with the most advanced forms of CAD rendering out there.

Screen

If you haven’t set eyes on a 5K display before, it’s a real treat. The iMac Pro isn’t the first iMac to have one, but all 27 inches of it are still incredibly impressive. The light distribution (up to 500 nits) is basically perfect across its 5120x2880 resolution with support for, apparently, one billion colours with a P3 wide colour gamut.

Apple does, but shouldn’t, label this a Retina display. It’s been doing it with products since 2010’s iPhone 4. The display here deserves better than that lazy piece of marketing.

It shows all manner of content completely and utterly brilliantly, from the humble word document right up to full on CAD renders, high-level graphic design and 4K video. Just remember that the display is available from £1,749 in the regular iMac line if this is key element.

Ports and connectivity

Thankfully the iMac Pro does not needlessly lose ports where the MacBook line recently has. You get a headphone jack, SDXC card slot, 3x USB-A 3.0, 4x Thunderbolt 3/USB-C and an Ethernet port that supports 10Gb speeds.

Thunderbolt 3 allows for high-speed data connections between iMac Pro and external SSDs or graphics cards, the latter something you may require depending on the task, even if you upgrade to the better AMD card initially.

These Thunderbolt ports allow for DisplayPort 1.2 and connections up to 40Gbps, while the USB-A 3.1 Gen 2 slots are no slouches at 10Gbps. Thunderbolt 2, HDMI, DVI and VGA are all supported here, but you’ll need one of Apple's growing range of adapters.

As per usual, the ports are all mounted on the back which keeps the design nice and clean on the front but often makes it awkward to plug things in.

Audio

The speakers on the iMac Pro are impressive for an in-unit system, but they aren’t mindblowing. If you’ve used speakers on an iMac before, you know what you’re getting: decent enough audio to enjoy music and movie viewings, but nothing approaching dynamic enough for music production - you’ll want to hook up your stereo speakers even on a machine this expensive.

Performance and benchmarks

After all that, how well does this thing actually run? Our 10-core, 128GB RAM review unit sits nicely as a marker of performance as its configuration means it can actually achieve the highest possible Turbo Boost speed out of the whole range of 4.5GHz.

Suffice to say this is a fast machine, and the iMac Pro in general is the fastest Apple has ever sold. We ran benchmarks against other iMacs in the range to demonstrate the performance differences.

Most are compared to the 2017 27in Core i7 iMac. Here are the results, which were run on software patched for both machines post-update following the Meltdown and Spectre vulnerabilities (High Sierra 10.13.2).

Geekbench 4.3 (64 bit)

The multi-core scores on Geekbench, a pure processing power test, are significantly higher on the iMac Pro with a mad 36,901. Bear in mind though that the i7 iMac is no slouch, and many, many users will not need the extra power afforded by the £9,188 Pro (the 3.4GHz iMac represented here costs from £1,749).

AJA System Test Lite

This test checks out the performance of the drive. We set both machines to 5K RED, 4GB, single file and disk cache disabled. Higher scores are better.

The write speed on the iMac Pro is much higher, while the read speeds are fairly comparable. This difference in write speeds can be attributed to the two separate hard drives in each storage configuration.

Unigine Valley

This test evaluates overall performance and stability while working through intense graphical workloads. We used the Extreme HD presets where higher is better. Of note here is the iMac Pro’s GPU reaching 91 degrees Celcius at one point during this process. Remarkably, the thermals dealt with it no problem.

Cinebench

We added the late 2015 5K iMac into the mix for the popular Cinebench benchmark (stick with us!) The OGL test is as incremental as one might expect on upgrading, but the render result is awesome with a sky high 2,023.

That’s second ever in our testing only to the Lenovo ThinkStation P900, which only scored 40 percent more because it had two 10-core chips. So the iMac Pro does incredibly well here.

After Effects

Using the CineWare plugin, our final test was with Adobe After Effects 2018 to give an idea of overall graphical processing. This measures the time taken to finish the tasks, so it’s the only test here where lower scores are better.

In all but one, the iMac Pro completes the tasks in less than half the time of the Core i7 iMac.

These benchmark results show two things. First, there’s no doubt this is the most powerful iMac ever. The second is that you probably don’t need the power. Only creative professionals rendering graphics and processing enormous video files will see the difference.

If you’re working in machine learning, more basic creative processes, in music production or similar, then you can likely settle for a far more affordable regular iMac.

Software

The iMac Pro runs macOS High Sierra with every standard Mac app you’d expect installed. There’s not actually any specialist program that Apple includes on the iMac Pro, and it's the same basic apps as you'd find on the cheapest Mac or MacBook in the entire range.

Of course, it’s the industry specific software that excels when booted up on this hardware. Apple offers to pre-install Final Cut Pro X (£299.99) and Logic Pro X (£199.99) at point of purchase, but you’ll rest assured that the vast majority of photo, video, CAD and music production software is going to run like a dream on the iMac Pro.

Again, the question only you’ll know the answer to is do you really require the power?