iMac Pro vs 27-inch iMac comparison review

Apple has the attention of the creative professional world right now with the launch of the new iMac Pro. However, there’s another iMac that could answer their needs.

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; and for more general buying advice remember to check our Mac buying guide.)

iMac Pro vs 27-inch iMac

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 new 27in iMac for 2017.

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 as much as £4,949.

That top-spec 27in iMac includes a quad-core Intel i7 Kaby Lake processor running at 4.2GHz (or Turbo Boost of 4.5GHz), 64GB RAM, a 2TB SSD and the AMD Radeon Pro 580 graphics with 8GB video memory.

Is that build-to-order iMac comparable to the iMac Pro?

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 64GB or 128GB), and a 1TB SSD (configurable to 2TB or 4TB).

The eight-core (or more) workstation standard Intel Xeon W processor and the Radeon Pro Vega graphics card make the iMac Pro a far more powerful machine. But do you really require that much power? If you’re editing 8K RED video, H.264 4K footage, or 50Mp RAW stills, perhaps you do. If you’re just looking for a superfast Mac, even if you’re a gamer, the iMac Pro is probably overkill.

iMac Pro vs 27-inch iMac: Graphics

Xeon vs i7 processor

How will the eight-core Intel Xeon W processor in the iMac Pro (with Turbo Boost of up to 4.5GHz) compare to the 4.2GHz quad-core Intel i7 Kaby Lake processor offered as a build-to-order option for the iMac (also with Turbo Boost up to 4.5GHz)?

The biggest and most obvious difference is the number of cores. Even if the i7 processor had a faster clock speed than the Xeon chip, the fact that it has fewer cores would mean it would be slower.

Increasing the processor speed doesn’t bring as much performance improvement as an increased number of cores. This is because more cores allow for more work to be performed at the same time.

The amount of cache is also noteworthy. This is the small amount of memory located directly on the processor. Core processors come with 8MB cache while Xeon CPUs top 60MB, although Apple says that the cache in the iMac Pro will max out at 42MB.

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. So you can expect more from the Xeon in this case too.

iMac Pro vs 27-inch iMac: Processor

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 i7 and Xeon processors have hyper-threading enabled by default so you will be able to take advantage of it on both Macs.

Note however that the i5 processor in the other iMacs doesn’t include hyper-threading. This is a feature you only get with the i7 iMac build-to-order option.

Finally, the power dissipation of the Xeon is better than that of the Core i7. This means that the Xeon can overclock more easily, as long as it has the means to keep cool.

There are some key differences between the two processors, with the Xeon coming out on top. But the i7 is still a very good choice.

This doesn’t mean that the 4.2GHz quad-core Intel i7 Kaby Lake processor would slow you down, of for that matter the Intel i5 chip that comes as standard. It really depends on the nature of your work.

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 vs Vega graphics

How will the AMD Radeon Pro 580 graphics with 8GB video memory compare to the Radeon Pro Vega graphics in the iMac Pro?

AMD says Vega will deliver its biggest graphics improvements in five years and Apple says that the Radeon Pro Vega is “over three times faster than any previous iMac GPU”. Sure enough, the iMac Pro trounced the iMac in every graphical benchmark and GPU stress test we threw at it.

Apple is using the Radeon Pro Vega 56 in the Mac Pro. This GPU offers 8GB HBM2 memory – that’s high-bandwidth memory. There is also a 16GB HBM2 memory option for the iMac Pro.

HBM2 memory is expected to be valuable to anyone working in virtual reality, so the new iMac Pro is ideal for that market.

iMac Pro vs 27-inch iMac: Graphics


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.

As for the Core i7, the chip used in the iMac officially supports 64GB, although some Core i7 chips support 128GB RAM.

16GB of RAM is likely to be sufficient for the vast majority of Mac users, though.

Should you wish to update the RAM at a later date it may be easier for you do do so it you own a 27in iMac, which has easily accessible RAM slots behind the screen.

There is no easy-access door on the back of the iMac Pro granting access to the RAM. Apple says the memory is not a user-upgradable, although it seems that a specialist would be able to perform the upgrade for you.


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.

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 £1,260/$1,400, so you could shave off more than £1,000 of the price of your build-to-order iMac, which would cost ‘just’ £3,689.


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.

iMac Pro vs 27-inch iMac: Display


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.

iMac Pro vs 27-inch iMac: Ports


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.

iMac Pro vs 27-inch iMac: Peripherals

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.

iMac Pro vs 27-inch iMac: Design