Apple 27-inch iMac with Retina 5K Display (2015)

It’s been a year since the first iMac with Retina 5K Display went on sale, wowing Expert Reviews with the quality and sharpness of the display. Since then, the iMac hasn’t seen any real competition: Dell’s 5K standalone monitor is the only other display to match its resolution, but it costs £2,000 alone. Against this, Apple could be forgiven for sitting on its laurels, slipping out a new model with a minor update, but the 2015 edition is a considerable improvement, not to mention better value.

Display

The 5,120x2,880 resolution is just as amazing today as it was when I first set eyes on it. As well as making everything exceptionally sharp, there’s enough resolution to comfortably use two applications side-by-side, or to even edit a 4K video while leaving enough room around the edges for your video-editing package’s controls. Text and icons are increased in size thanks to OS X El Capitan’s brilliant scaling, so you get the benefit of a sharper screen without having to squint at the interface.

So far, it’s the same story as last year, but the 2015 27-inch iMac now has a wider 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 a lot 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 99.9% of the sRGB and DCI P3 colour gamuts. With a contrast ratio of 1,166:1 and brightness of 466cm/m2, this is definitely one high-quality panel. There’s only one minor issue: the screen’s a little dimmer into the corners (around 10% in my measurements), which could be a problem for professionals.

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 bandwidth required. 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. When we get Thunderbolt 3, which has enough bandwidth, we may see future 27-inch iMacs re-instate target mode, but for now it’s off limits.

Performance

Apple has upgraded the internals to use Intel’s latest Skylake processors, with my review sample shipping with a 3.2GHz, quad-core Intel Core i5-6500 CPU and 8GB of RAM (upgradeable to 16GB or 32GB). In the Expert Reviews 4K benchmarks, the iMac scored 100 overall - roughly 10% quicker than last year’s model, which scored 91. That’s in-line with the speed boost we’ve seen moving from previous generation Haswell chips to Skylake. In short, this year’s iMac is still very quick, although you probably wouldn’t notice a lot of difference compared to last year’s models. If you need more speed, then you can upgrade to a 3.3GHz Core i7.

Apple has used a 2GB AMD R9 M390 graphics chip in the mid-range model, with a slightly slower R9 M380 for the entry-level iMac; if you buy the top-end model this is upgraded to an M395 with an optional upgrade to a 4GB M395X. They are all based on mobile GPUs, and none are particularly high-speed, so you won’t be able to play games at the screen’s full resolution. Instead, what you get are graphics chips that are capable of driving the 5K display smoothly and that are more than quick enough for professional applications.

Storage

The entry-level model ships with a 1TB 7,200rpm hard disk, but I can’t recommend it as OS X really needs flash storage to operate as fast as it can. Instead, you should opt for the 1TB Fusion drive at a minimum, which combines 24GB of fast flash storage with a regular hard disk: your most commonly used files and apps are stored in flash, while the hard disk gives you plenty of capacity. It works, too, with my test Mac booting quickly and feeling as responsive as a computer with flash only in it. As you start to fill up your Mac, the flash storage will fill up quite quickly, so the 2TB (£240) or 3TB (£240) Fusion Drives might be worth upgrading to, as they have 128GB of flash storage. Performance in our tests was quick, and I clocked the Fusion Drive has managing 687MB/s read speeds and write speeds of 170MB/s. If you want the best performance, you’ll need to upgrade to a flash-only model: 256GB, 512GB and 1TB options are available. These cost an extra £80, £320 and £720 respectively, which makes the Fusion Drives the better value option by far.

Build quality

The one thing that hasn’t changed is build quality, and the 27-inch iMac remains one of the best-made, most attractive all-in-one computers that I’ve ever reviewed. The full metal body and stand give it that distinctive Apple look, while reassuring you that it’s an expensive and rugged computer. If I have one minor complaint it’s that the screen doesn’t have any height adjustment: you can only tilt it. Even so, this is one computer that I’d proudly have out on display.

Ports and expansion

Due to the thin screen, all of the ports are round the back of the screen. It’s a little inconvenient if you spend a lot of time plugging in memory cards and USB devices, but the iMac swivels easily on its base, so the ports are fairly quick to get to when you need them. At the back you’ll find four USB3 and two Thunderbolt 2 ports, alongside a Gigabit Ethernet adaptor (there’s built-in 802.11ac Wi-Fi), an SDXC card slot and a headphone output: in other words everything you really need to use.

Magic Keyboard, Magic Mouse 2 and Magic Trackpad 2

With this year’s iMacs come the new range of Magic wireless peripherals, which finally have integrated batteries that are charged via their Lightning ports. Apple has redesigned the keyboard so that it takes up less room but has bigger keys with less travel. It took me a little while to get used to it, coming from an older USB Mac keyboard, but once I did I found the new keyboard to be extremely comfortable and quick to type on. Apple definitely knows how to make a good keyboard and this is the best desktop version, yet.

The Magic Mouse 2 isn’t a big improvement over the previous model and I’m not a big fan of it. I find that it’s a little uncomfortable to hold, although the integrated touch sensors for scrolling and moving back/forwards in apps is useful. That said, I know people that swear by this mouse, so it’s definitely a matter of preference. The Lightning port is in the base, so you can't charge it while you use it, but it charges very quickly - as little as two minutes connected will give you several hours of use.

Special praise has to be saved for the Magic Trackpad 2, which costs £44 extra if you swap the bundled mouse for it, or £109 if you buy it in addition. That sounds like a lot of money, but OS X is designed to be used with a Trackpad, with so many multi-touch gestures that make navigating the web and switching apps a lot easier than resorting to the keyboard. This time around the Trackpad supports Force Touch, which is brilliant, as I’d got so used to using it on my MacBook that I missed it when using the old Magic Trackpad. In other words, my advice is: hang the expense and buy the Magic Trackpad 2, as it’s brilliant.

Conclusion

Although the 27-inch iMac starts at £1,449, you should at least buy the Fusion Drive for an extra £80 or, better yet, upgrade to the next model, which has the Fusion Drive and faster graphics, and costs £1,599. Given that this is a computer aimed at professionals and enthusiasts, you may want to upgrade that model to the 2TB Fusion Drive and 16GB of RAM, taking the final price to £1,919.

Now, neither of these prices sound particularly ‘cheap’, but you have to take this product into context. If you were to buy a 27in 5K monitor from Dell, you’d have to spend over £2,000 and that wouldn’t get you a computer at all.

When you look at it like that, the 27-inch iMac with 5K Retina Display isn’t just amazing value, it’s a complete steal. Given the quality of the display, the speed of the internals, the build quality and the amazing wireless peripherals, there’s nothing out there that can touch this computer: it’s the ultimate all-in-one for professionals and for those that want the best, winning it a Best Buy award. If this isn't quite what you're after, our regularly updated best desktop PC guide will have something that suits you.