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27-inch iMac with Retina 5K display (2017) review: The fastest, most stunning iMac ever made

Our Rating :
Price when reviewed : £1749
inc VAT

An amazing display with so many pixels makes the 27-inch iMac a real winner and puts itself in a league of its own


  • Stunning 5K display
  • Performance


  • Price

UPDATE: It has been over one year since I originally wrote my review, and yet, my verdict hasn’t changed. The 27-inch iMac with Retina 5K Display is still a one of a kind machine, which offers an incredible package for those looking to get a fantastic, colour accurate display, and a Mac.

The 27-inch iMac with Retina 5K was first seen in October 2014 and has been irregularly updated. On 5 June 2017, Apple announced its latest iMac that features Intel’s Kaby Lake processors. But don’t think that’s the only difference Apple has managed to conjure since its 2015 iteration of the iMac 5K.

With new features and a brand-new processor, can the 27-inch iMac with Retina 5K display still be king of the crop?

27-inch iMac with Retina 5K display (2017) review: What you need to know

After more than a year of waiting, the new 5K iMac is an improvement over the 2015 model in almost every way. Its new Kaby Lake processor is fast; the screen is even brighter; and it has faster memory, a more powerful AMD graphics chip and two Thunderbolt 3 (USB Type-C) ports for faster transfers.

There’s so much to like about the new iMac, but its £1,749 price tag might put off a few consumers. It is expensive, but there isn’t anything else quite like the 27-inch iMac with Retina 5K. It looks stunning with and without the screen switched on and the new hardware inside peps up performance nicely. The best all-in-one PC just got better.

27-inch iMac with Retina 5K display (2017) review: Price and configurations

Apple raised its prices in late 2016 following Brexit. The 27-inch 5K iMac’s base price used to be £1,449, but is now £1,749. This price increase also applied to iMacs prior to the 2017 launch. This makes the iMac slightly more expensive, and as someone who wants to experience an iMac for the first time, its price does seem very steep.

Buy the 27in iMac from John Lewis

The new 5K iMac comes in three separate base configurations, which are distinguished easily by the processor housed within it. There is a 3.4GHz model from £1,749, 3.5GHz from £1,949 and 3.8GHz model from £2,249. Each has its own configurations to choose from, including the mid- and high-range models, which can be configured with an Intel Core i7 clocked at 4.2GHz. You can find the full range of options through Apple’s website.

The model I received has the following configuration:

  • Model: 27-inch iMac with Retina 5K Display
  • Processor: 3.4GHz quad-core 7th-generation Intel Core i5, Turbo Boost up to 3.8GHz
  • RAM: 8GB 2400MHz DDR4
  • Storage: 1TB Fusion Drive
  • Graphics: Radeon Pro 570 with 4GB video memory
  • Peripherals: Magic Mouse 2 and Magic Keyboard – British

The above configuration is the base model, which comes in at £1,749. Below are extras that you can include:

  • 16GB RAM +£180
  • 32GB RAM +£540
  • 2TB Fusion Drive +£180
  • 256GB SSD +£90
  • 512GB SSD +£270
  • 1TB SSD +£630
  • Magic Trackpad 2 (replacing the Magic Mouse 2) +£50
  • Magic Trackpad 2 & Magic Trackpad 2 +£129

The extras are rather expensive and aren’t necessary for most.

READ NEXT: Best monitor: The best budget, 5K, 4K, WQHD, 1080p monitors

27-inch iMac with Retina 5K display (2017) review: Display

Its Retina 5K (5,120 x 2,880) display is just as amazing today as it was in 2015. The new iMac uses the same IPS technology as before, which covers the DCI-P3 colour space but is brighter. Apple claims it has 500nits of brightness, and after putting it through the X-Rite i1Display Pro calibrator, the 5K iMac does achieve a 514cd/m2 maximum brightness.

This makes it the brightest iMac ever and the brightest display I’ve ever set my eyes on. Most monitors tail off at around the 300-400cd/m2 mark, so having that extra level of brightness might seem blinding to some, but for those using the 5K iMac in a bright sunlit room, the new display makes for comfortable viewing. Text and icons are also increased in size thanks to macOS’s brilliant scaling capabilities, so you get the benefit of a sharper screen without having to squint at the interface.

Much like the 2015 model, the new 27-inch iMac has a wide colour gamut, using the DCI P3 colour space. It means that the panel is capable of displaying 25% more colours than a regular monitor that uses the sRGB colour space. 

When you take a photo using a camera in RAW mode, your camera captures more detail than a typical screen can display. This results in clipping, where subtle changes in colour are blended into one solid lump of colour that your display can show. The same goes for a lot of videos, too. With the DCI-P3 colour space, the iMac can retain more of the original colour.

Looking at sample photos and comparing the DCI-P3 versions to the sRGB versions, there’s a definite improvement, with colours getting more vibrant and subtle detail coming back into the picture. For photographers, this screen could make a big difference, getting them much closer to the detail that was originally captured.

Only new photos or videos that you import (or convert) into a DCI-P3-compatible application, such as Adobe Lightroom CC, will be able to show additional detail: existing media will most likely have been clipped down to sRGB. As such, the P3 colour mode is largely a feature that professionals or enthusiasts will appreciate and, once they start using this display, they’re going to love it.

Testing the screen with our colour calibrator, we found that the screen was capable of 99.8% of the sRGB and 98.5% of DCI-P3 colour gamuts. At a measured 740:1 contrast ratio, it might not be the best panel around, but it’s definitely one of the better-quality displays out there.

Sadly, the iMac still can’t be used as a display target for use with a MacBook or other external device. It all comes down to the timing controller and Apple’s stance on using any iMac newer than the late 2014 model in Target Display Mode. This display has a single timing controller and, internally as it’s an all-in-one, the bandwidth to drive the monitor in one go. Dell’s 5K monitor has two timing controllers and requires two Thunderbolt ports to drive it.

Yet again, there’s no touchscreen integration. This is partially due to the limitations Apple has put on macOS. No macOS device, including the latest MacBooks, has a touchscreen display. Coming from a new Windows 10 or 8 laptop, you might find yourself missing this functionality. Personally, I don’t use touch on my main desktop computer but I do use it on occasion on my laptop. Given the 5K iMac is a visually stunning device, which can be used for watching high-res movies, a touchscreen display might have proved popular.

READ NEXT: Iiyama ProLite XB2779QQS review: An iMac-style 5K monitor at a tempting price


27-inch iMac with Retina 5K display (2017) review: Performance

Apple has upgraded the internals to Intel’s latest Kaby Lake processors. My review sample comes with a 3.4GHz, quad-core Intel Core i5-7500 CPU and 8GB of RAM (upgradeable to 16GB, 32GB or 64GB).

The iMac achieves a 4,803 single-core and a 13,640 multi-core score in Geekbench 4, that’s much faster than the 13in Apple MacBook Pro 3.1GHz Intel Core i5-7267U (Kaby Lake), which manages a 4,365 and 9,223 score respectively.

In the Expert Reviews 4K benchmarks, the 2017 5K iMac achieved an overall score of 109, a 9% improvement on the 2015 model. Retrospectively, the 2015 iMac scored 100 overall, roughly 10% quicker than the 2014 Haswell model, which scored 91. That’s in line with the speed boost we’ve seen moving from previous-generation Haswell chips to Skylake, and Skylake chips to Kaby Lake.

In short, this year’s iMac is still very quick, although you probably wouldn’t notice much difference compared to last year’s models. If you need more speed, then you could always upgrade to the 3.5GHz and 3.8GHz Core i5 or the beastly 4.2GHz Core i7.

Apple has used a 4GB AMD Radeon Pro 570 graphics chip in its lowest-range model, with a slightly faster Radeon Pro 575 4GB in its mid-range and a Radeon Pro 580 in the highest available model. The Pro 570 faired very well in GFXBench, with a 46.5fps onscreen performance in Manhattan 3 and 59.9fps in the T-Rex benchmark.

This means that you’ll be able to game on the new 27-inch 5K iMac, whereas the 2015 model struggled to cope due to the mobile chip inside (the AMD R9 M380, M395 and M395X). This represents a major improvement in the graphics department, as you won’t be limited to downscaling games. Still, don’t expect to play AAA titles on the new 5K iMac – that’s if you can get them to run on macOS in the first place, of course, but that’s a whole different issue.

Buy the 27in iMac from John Lewis

Another improvement is in its memory. Apple has upgraded from a 1,867MHz DDR3 RAM to a much faster 2,400MHz DDR4 RAM. This helps with everyday tasks, but will also power through heavy multitasking demands. If you feel your current 2015 or 2014 5K iMac is struggling with several applications simultaneously open, then it might be worth upgrading to the 2017 model.

Continue to page 2 for the storage, build quality, ports, peripherals, and the verdict

Pages: 1 2

Core specs
Processor3.4GHz quad-core Intel Core i5-7500
Processor socketLGA-1151
Memory type2400MHz DDR4
Maximum memory32GB
MotherboardNot disclosed
Motherboard chipsetNot disclosed
Ports and expansion
Front USB ports0
Rear USB ports4x USB3
Other ports2x Thunderbolt 3 (USB-C)
Networking1x 10/100/1000BATE-T, 802.11ac
Case typeAll-in-one
Case dimensions HxWxD516x650x203m
Total storage1TB fusion drive
Memory card readerSDXC
Optical drive typeN/A
Graphics cardAMD Radeon Pro 570 (4GB of VRAM)
Graphics/video ports2x Thunderbolt 3 (USB-C)
Sound cardApple
Sound card outputs3.5mm headphone jack
Speakers2x stereo
DisplayApple 27in integrated
Native resolution5,120 x 2,880
Other hardware
KeyboardApple Magic Keyboard 2
MouseApple Magic Mouse 2
ExtrasApple Magic Trackpad 2 (£129)
Operating systemApple macOS X 10.12.5 Sierra
Operating system restore optionInternet

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