Review: iMac with Retina 5K display


When Apple announced the iMac with Retina 5K display toward the end of 2014, it didn’t come as a shock. The Cupertino-based company slimmed down its previous-generation iMacs two years earlier, and it felt like a matter of time before they would join a growing fleet of Retina-equipped products that now includes the iPhone 6, iPad Air 2 and the new MacBook.

Going one further than 4K, the Retina iMac’s 5K display features a pixel-resolution of 5,120 x 2,800, which lends it more than 14.7 million pixels – four times that of the non-retina 27-inch iMac.

But instead of running at its native resolution, which would render elements on the desktop uncomfortably tiny to use, the new iMac uses the same pixel-doubling scaling as Apple’s Retina smartphones, tablets and notebooks to make icons, text and Retina-coded apps appear incredibly sharp and detailed.

5K iMac

Going from an iPhone 3GS to an iPhone 4 (and an iPad 2 to an iPad 3) in the past, I’ve become accustomed to the leap in clarity that upgrading to one of Apple’s Retina devices brings – but the new iMac is on another level.

After ogling its display for several weeks, going back to a regular monitor is like stepping back into a previous era. At 217ppi, it’s technically short of the MacBook Pro with Retina’s 228ppi, but its larger display means that you can do more – whether it’s editing high-resolution images without having to zoom out, or editing 4K movies at 100% in Final Cut Pro X with the timeline in full view.

Even everyday tasks such as browsing the web, answering email and chatting on social networks are more enjoyable and less taxing on the eyes.

Cost control

Of course, the experience doesn’t come cheap. Starting at £1,999 (US$2,499 or AUS$2,999), the new iMac can’t be had with loose change and Apple is pitching the machine at multimedia types who actually need all those pixels – from videographers to image editors – in addition to regular computer users with deep pockets.


The base model gets you a 3.5GHz (Turbo Boost to 3.9GHz) quad-core Intel Core i5 Haswell CPU, 8GB of RAM, a 1TB Fusion Drive and AMD Radeon R9 M290X 2GB graphics. Souping it up to the maximum config adds an extra £1,520 (around US$2,267 or AUS$2,913) to the total cost. In comparison, a similarly specced non-Retina iMac starts at £1,599 (US$1,999 or AUS$2,449), a difference of £400 (around US$597 or AUS$766).

It’s worth bearing in mind that Apple’s recent OS X 10.10.3 Yosemite update means that Late 2013 27-inch iMac and later can now drive a 4K display, which can now be had for under £300 (around US$448, or AUS$575). That means that you can pick up the latest non-Retina 27-inch iMac – still an attractive machine in itself – and a 4K display as a secondary monitor for less than the cost of a Retina iMac.


However, if you’re not prepared to accept anything less than 5K without digging deep for the new iMac, options are limited where OS X is concerned. While Yosemite’s latest update includes support for Dell’s 27-inch UP2715K 5K display, it retails for a cool £1,200 (around US$1,793 or AUS$2,300).

Moreover, that monitor is only currently supported by the Retina 5K iMac (which you’re trying to avoid) or the Late 2013 Mac Pro, which at a base cost of £2,499 (US$2,999 or AUS$3,999) is even less affordable than the Retina iMac itself.

And no: the Retina iMac doesn’t support Target Display Mode, unfortunately, meaning that you can’t connect computers, consoles and other devices via Thunderbolt or mini-DisplayPort to display their contents; it’s a real shame too.


The iMac with Retina 5K display’s design is unchanged from the previous-generation 27-inch iMac, and it’s still one of the most attractive computers around. The processor, graphics, memory, storage and other components are housed in the area behind the display, which measures 5mm thick along the bottom edge and gets wider toward the centre of the display’s back panel.

It’s impossible to tell just by looking, but the new iMac has received a re-engineered panel that measures 1.4mm and apparently uses 30% less power than the non-Retina 27-inch iMac. According to Apple, this was done using a combination of energy-saving technology borrowed from the iPad Air 2 that separates pixels more effectively to better conserve energy, in addition to switching to a more energy-efficient type of LED.


The iMac 5K with Retina display is also available with a VESA stand for mounting onto a wall. The default stand doesn’t provide much flexibility, and can be tilted forwards or backwards by around 60 degrees. There’s no height adjustment either, meaning you’ll probably want to pick up a third-party iMac stand rather than balancing what is an expensive computer on a wobbly pile of books.

Here is the spec sheet of the base model provided to TechRadar for review:


  • Processor: Intel Quad-Core Intel Core i5 processor (Turbo Boost up to 3.9GHz)
  • Operating System: OS X 10.10.3 Yosemite
  • Memory: 8GB of 1600MHz DDR3
  • Display: 27-inch (diagonal) Retina IPS display (5,120 x 2,880)
  • Graphics: AMD Radeon R9 M290X GPU with 2GB of DDR5 memory
  • Storage: 1TB Fusion Drive
  • Camera: FaceTime HD Camera
  • Networking: 1/10/1000BASE-T Gigabit Ethernet, 802.11a/b/g/n Wi-Fi
  • Connectivity: 1 x headphone, 1 x SDXC card slot, 4 x USB 3.0, 2 x Thunderbolt 2, 1 x Mini DisplayPort, Support for DVI, VGA and dual-link DVI (adapters sold separately)
  • Audio: Stereo speakers; dual microphones; headphone port/optical digital audio output (mini-jack)
  • Dimensions: 51.6 x 65 x 20.3 (H x W x D)
  • Weight: 9.54 kg (21 pounds)

The base Retina iMac comes with a 3.5GHz quad-core Intel Core i5 CPU (Turbo Boost to 3.9GHz), and can be upgraded to a 4.0GHz quad-core Intel Core i7 (Turbo Boost to 4.4GHz). Opting for the Core i7 upgrade gives you the advantage of Hyper Threading, where each of the CPU’s four cores can run two threads for eight virtual cores, something the quad-core i5 is unable to do.

Main memory starts at a meagre 8GB, but can be increased to 16GB or 32GB – for a cost. In terms of storage, the iMac comes with a 1TB Fusion Drive that combines a hard drive with a solid state drive for regularly accessed data. Alternatively, the iMac can be configured with a 3TB Fusion Drive or 256GB/512GB/1TB of solid-state storage.


For graphics, the base iMac is configured with an AMD Radeon R9 M290X – a dedicated mobile GPU that comes with 2GB of GDDR5 vRAM. For better handling GPU-intensive applications, it can be upgraded to be a Radeon R9 M295X with 4GB of DDR5 vRAM.

The iMac comes with OS X Yosemite 10.10.3 installed, which has been designed especially for high pixel-density displays. However, while Apple’s own apps and most creative packages are optimised for high-DPI resolutions, many still aren’t – and you might find yourself running into blurry images and icons if you come across ones waiting to be updated.

The OS can also cause some issues when it comes to UI elements looking small – even when running in Retina-optimised mode. The controls in apps such as photo editing suites can be tiny and way off to the side (it’s here that keyboard shortcuts can come in handy).


While Apple’s iMac line isn’t designed to be taken apart and modified, like previous iMacs the Retina iMac does present some scope to be upgraded. The easiest component to change RAM, as modules are easily accessible thanks to upgrade slots at the rear of the machine.

As iFixit notes in its teardown of the Retina iMac, you’ll need a steady hand, a set of custom tools and some spare time on your hands should you want to prise it open and replace components such as the hard drive and CPU.

iFixit rated the Retina iMac 5 out of 10 for its upgrdability difficulty (with 10 being the easiest to repair), noting the trickiness of prising the display’s glass and LCD apart (they are now sealed together rather than held together by magnets), and the need to apply fresh double-sided sticky tape to reseal the iMac into its original condition once finished.

Performance and benchmarks

The iMac 5K with Retina performed admirably during my time with it no matter how much I threw at it. It boots in around 14 seconds from cold thanks to the SSD part of its Fusion drive, and the Radeon GPU proved more than capable of pushing pixels when editing high-resolution images with little or no slowdown.

While it managed to chew through any game I threw at it with the resolution turned down, the mobile graphics chip and its 2GB of virtual memory struggled to run anything at the iMac’s native 5K resolution with anything approaching playable frame rates.



  • Xbench: Overall: 623; CPU: 391.17
  • Cinebench R15 Single Core: 142cb; Multi Core: 540cb; Open GL: 91.80 fps
  • Unigine Heaven 4.0 Medium quality (2,560 x 1,440): Score 741
  • Unigine Heaven 4.0 Ultra quality (2,560 x 1,440): Score 451
  • NovaBench: Score: 963; Graphics 185
  • Batman: Arkham City (High, 5,120 x 2,880): Minimum: 7fps; Maximum: 26fps; Average 22fps
  • Batman: Arkham City (2,560 x 1,440): Minimum: 28fps; Maximum: 82fps; Average: 70fps
  • Tomb Raider (5,120 x 2,880): Minimum: 10fps; Maximum: 19.7fps; Average: 14.7fps
  • Tomb Raider (2,560 x 1,440): Minimum: 37fps, Maximum: 59fps, Average: 49.2fps

I fired up Final Cut Pro and took it full screen to see some 4K video footage at 100% in the corner, with the timeline and other clips visible around it, for live editing. Again, 4K video playback was smooth as it went through the timeline, without any pausing or hanging between clips – of course, the SSD portion of the Fusion Drive was probably in use here. Even with three browsers running at once with 10 or more tabs open in each, watching a 4K video on YouTube at full screen produced no stuttering or choppiness.


Gaming and display

Gaming on the iMac was more of a mixed bag. If your intention is to play modern titles in 5K, coughing up extra for the R9 M295X with 4GB of video memory would help when loading high-resolution textures in games. However, the R9 M290X with its 2GB of video memory had no trouble handling Batman, Borderlands: The Pre-Sequel and Tomb Raider at 1440p with all settings set to maximum, and they still looked incredible. Only when the resolution was upped to 5K did frame rates drop to unplayable levels.

The display’s benchmarks make for particularly pleasing reading. Using an X-Rite i1Display Pro colorimeter, I was able to record a room illuminating brightness of 459.5 cd/m2 (or nits). Screen uniformity was mainly impressive with a blip or two, showing a shaded patch in the far left-hand side of the screen that measured 17% darker than the centre of the panel and a patch in the top centre edge of the panel that deviated 16.65% in brightness compared to the centre. The display showed a fairly even brightness everywhere else.

The iMac measured impressive inky black levels of 0.3785 cd/m2, and a contrast ratio of 1213.9:1, which combined gave an average delta of 1.54 (anything below 2 is considered good). The iMac covered 98.6% of the sRGB colour space, which should prove sufficient for photography professionals requiring decent colour accuracy.


On the outside, the Retina iMac remains essentially identical to the regular 27-inch iMac. It makes it kind of an astonishing thing to have on you desk in one tidy package. Apple’s best desktop yet? Probably. Surely, even.

We liked

The iMac 5K with Retina has one of the best displays that money can buy. The modern computer experience (particularly so on Yosemite) is hugely visual, and having a super-sharp Retina display just makes it a joy to use. It’s one of the best all-round computers on the market for photography enthusiasts, designers and other multimedia editors seeking a compact all-in-one with a vibrant and colour-packed display.

And it’s all wrapped up in a relatively compact package that’s simple to set up and won’t take up much room on your desk. There’s plenty of ports (including the highly useful Thunderbolt 2), and the ability to easily upgrade RAM, hard drive, CPU and other components (albeit with some difficulty) will be welcome by anyone worried about the lifespan of such a wallet-intimidating machine.

We disliked

The obvious downside to the iMac is that it’s expensive, but when you consider the cost of a 5K monitor and an equivalent-specced PC, there’s not much in it. Dropping down to a 4K monitor, on the other hand, opens up combinations that will cost a lot less than the Retina imac.

The absence of Target Display Mode is a big loss, especially when previous iMac models permitted the connection of secondary devices. It wouldn’t be surprising if some of the pros it should target will be hoping for an equivalent Cinema Display to connect to a Mac Pro.

iMacs have never been famed for gaming, and gamers plumping for a Retina iMac will need to temper expectations. Though it depends on the game, more recent titles simply won’t run at acceptable frame rates on the entry-level’s mobile GPU. Opting for the Radeon with 4GB of video memory may help with this, but without benchmarking that machine it’s impossible to say for sure.

Final verdict

The iMac 5K with Retina has one of the best displays that money can buy. The modern computer experience (particularly so on Yosemite) is hugely visual, and having a super-sharp Retina display just makes the operating system a joy to use. Be warned, though: once you’ve clasped eyes on its crispness you’ll find it difficult to go back to what you were using before. You may have to save up for months on end to afford one, but the longevity afforded by the display and means that it will serve you well for some time.