Our Verdict
If you need the extra cores, superior graphics, 10Gb ethernet, HBM2 graphics memory and ECC RAM, and the four Thunderbolt/USB Type-C ports offered only by the iMac Pro, your decision is easy. But the Pro machine is seriously expensive, and you need to think long and hard about exactly how much processing welly you really need. It’s likely you can customise one of the 27-inch iMacs to a spec that’s suitable for your needs and save a shed load of cash.
Price When Reviewed
Apple iMac Pro (2017): Base model $4,999
Apple 27in iMac (3.0GHz, 6-core, 8th-gen, 2019): $1,799
Apple has the attention of the creative professional world right now with the iMac Pro. However, there’s another iMac that could answer their needs – and it’s been updated for 2019.
In this comparison we ask the question, should you buy a 27in iMac or the iMac Pro? We compare and contrast the two machines on design, features, specs and value for money.
If you do reach a decision you can buy the iMac Pro from £4,899 in the UK or from $4,999 in the US. And the 27in iMac starts at £1,749 in the UK and $1,799 in the US.
(If you’re wondering what the Mac Pro might offer when Apple introduces that new model, read our new Mac Pro preview; we also have this article about what the new iMac Pro might offer, and for more general buying advice in our Mac buying guide.)
Pricing and configuration options
The first thing to look at is the price – which can vary considerably depending on many optional extras and upgrades you want to tag on.
The iMac Pro has a high price attached to it, starting at around £4,899 inc VAT (or $4,999). If that’s too much money for you to consider paying for a new Mac you might as well stop reading and head to our review of the 27in iMac here.
You can buy a 27in iMac for £1,749/$1,799. However, if you were to spec up your iMac to the max, you could spend nearly £4,904/$5,249.
That top-spec 27in iMac includes a 9th-gen 8-core Intel i9 processor running at 3.6GHz (or Turbo Boost of 5.0GHz), 64GB RAM, a 2TB SSD and the AMD Radeon Pro Vega 48 graphics card with 8GB HBM2 video memory.
The standard configuration of iMac Pro comes with an eight-core Intel Xeon W CPU (configurable to 10-, 14- or 18-cores), 32GB RAM (configurable to 64- or 128GB), and a 1TB SSD (configurable to 2- or 4TB).
Is that build-to-order iMac comparable to the iMac Pro? We’ll look in more detail at how the specs compare below, but as an overview, in both cases you are getting eight-core chips and 8GB GPUs (albeit different models).
Xeon W vs Core i9 processor
How will the 3.2GHz eight-core Intel Xeon W processor in the iMac Pro (with Turbo Boost of up to 4.5GHz) compare to the 3.6GHz eight-core Intel Core i9 processor offered as a build-to-order option for the iMac (with Turbo Boost up to 5.0GHz)?
Well they have the same amount of cores, but the 9th-gen chip in the regular iMac has higher clock speeds. In that respect, the regular iMac is better but the top Xeon has a large cache at 42MB compared to 16MB. The cheapest iMac Pro has 19MB, though, so there’s not much in it at the comparable price.
For many applications cache is another important contributor to performance. For example, if two processors have the same GHz but different amounts of cache, the one with more cache will perform better.
Hyper-threading is another feature to take note of. Hyper-threading allows multiple tasks to be performed at the same time by the same core. Both the Core i9 and Xeon processors have hyper-threading enabled by default so you will be able to take advantage of it on both Macs.
We have run benchmarks on the processors in the build-to-order 3.6GHz 8-core 27in iMac for 2019 and the iMac Pro (note that iMac Pro model tested was the Intel Xeon W-2150B 3GHz, 10-core, 128GB 2666GHz DDR4 ECC RAM, and 2TB drive, so not the model we are describing in this article, but interesting nonetheless).
The graphics card will also have a big impact on overall performance, and we’ll talk about that next.
If you want to find out more about the different types of processor available in the Mac range read this: How to choose the best Mac processor for your needs.
Radeon Pro graphics
Now with the updated specs for 2019, the 27-inch iMac with custom options can come with a Radeon Pro Vega 48 graphics card. At the cheapest option, there’s a Radeon Pro 570X with 4GB of VRAM.
The Vega 48 with with 8GB of HBM2 memory is much closer to the iMac Pro now with its Radeon Pro Vega 56, also with 8GB HBM2 memory.
We have graphics benchmarks for the 2019 build-to-order 27in iMac with Radeon Pro Vega 48, and the 2017 iMac Pro with the Radeon Pro Vega 64 as seen below. As you can see the two cards are pretty comparable.
ECC RAM
Another factor in the iMac Pro’s favour is the inclusion of ECC memory – Error-Correcting Code memory.
ECC includes special circuitry for testing the accuracy of data as it passes in and out of memory so it can detect and correct any corruptions. This kind of memory is suited to scientific or financial applications that cannot tolerate any data corruption.
There are some other significant differences. The Xeon chip in the iMac Pro will support more memory – Apple says up to 128GB, but there are some Xeon chips that support more than 1TB of memory. The computer is configurable up to 256GB.
As for the Core i9, the chip supports up to 128GB RAM, but you can also configure the iMac up to 64GB.
Storage
The new iMac Pro offers a 1TB SSD as standard, with the option of up to 4TB. The top of the range build-to-order iMac offers a 2TB SSD and comes with a 1TB Fusion Drive at the least.
Since we are comparing the build-to-order iMac with the standard iMac Pro, in this case you would get more storage for your money if you bought the non Pro iMac.
That 2TB SSD costs you a whopping £990/$1,100, so you could shave a lot off vs the iMac Pro in this respect.
Display
The 27in screen on the iMac Pro will offer the same 5,120×2,880 resolution 5K Retina display, with the same 500 nits of brightness, 14.7 million pixels, P3 colour gamut and support for over a billion colours, as the standard 27in iMac.
There is no reason in terms of display to choose the iMac Pro over the standard 27in iMac.
Ports
While the standard 27in iMac offers two Thunderbolt 3/USB Type-C ports, the iMac Pro offers four. This means you could connect two additional 5K monitors to your iMac Pro for a whopping 44 million pixels, and hook up two high-performance RAID arrays and enjoy 40Gb/s transfer speeds.
One other thing the iMac Pro offers that the standard iMac doesn’t is 10Gb Ethernet.
The standard iMac offers a 1Gb Ethernet socket. This means that sharing files on the iMac Pro, or working with high-performance network storage, will be up to 10 times faster.
It also includes an SDXD card slot that supports UHS-II (that’s Ultra High Speed) for even faster data transfer rates.
Design
The most obvious design difference between the two machines is the Space Grey case of the iMac Pro, which gets a brand new Space Grey Magic Keyboard, Magic Mouse and Magic Trackpad to match the new look.
The real design changes are on the inside. Apple has had to completely rethink the thermal architecture of the iMac in order to house the new components inside the Pro. You’re unlikely to see any evidence of this other than the fact that there are two fans inside the iMac Pro and a pair of horizontal vents across the bottom of that machine, while a regular iMac has a single fan plus one vent.
You can also read our comparison of all the pro Macs.
Author: Karen Haslam, Editor
Macworld editor since 2008, Karen has worked on both sides of the Apple divide, clocking up a number of years at Apple's PR agency prior to joining Macworld almost two decades ago.
Karen's career highlights include interviewing Apple's Steve Wozniak and discussing Steve Jobs’ legacy on the BBC. Her focus is Mac, but she lives and breathes Apple.