New 21.5-inch 3.1GHz iMac with Retina 4K display review – Macworld UK

The new 21.5in iMac has finally gained a Retina display. It’s a 4K display, as opposed to the 5K display that the 27in Retina iMac gained last year.

These Macs haven’t been updated since 2013 so this update was long overdue.

New 21.5in iMac with Retina display: Display

Only the top of the range model gains the 4K display, the other 21in models have been updated with new processors, but they retain the older display – and the prices don’t change (we’ll look at those iMacs separately).

The price of the top of the range 21in iMac hasn’t changed either, as we discuss below, but at £1,199 it’s not the cheapest Mac with a Retina display you can buy. The 13-inch Retina MacBook Pro costs £999. But that Mac has a smaller display and a slower processor, so it’s certainly not a bad deal.

The 21in Retina display offers 4096 by 2304 pixels, that’s 9.4 million pixels and it means there are now four pixels doing the work that only one used to do. It’s also a vastly broader work area than an that offered by any of Apple’s Retina laptop screens.
If it’s an even bigger Retina display you are after, the entry level 27in iMac now offers one, but it costs £1,449, that’s £250 more.

There is more to the Retina display than being able to see subtle details that you were blind to on a low res screen. Because the pixel count is so high, there’s a lot of flexibility with a Retina display. These screens can be set to alternate resolutions without sacrificing image quality. For example, if you want everything to be a little bit bigger you can set the 4K iMac to emulate a smaller monitor in the Display preference pane. Or if you want, you could set the iMac to display a higher resolution giving you more room to work.

According to Apple this display also offers an expanded colour space thanks to new red-green phosphor LEDs that enable the displays to display a wider range of red and green light than before, allowing them to display 25 percent more colours. Hence, these displays are capable of displaying 99 percent of the P3 colour space. Not bad, although it probably won’t matter to you unless you work in the video or graphics industries.

New 21.5in iMac with Retina display: Price

The new top of the range 21.5in iMac gains this new 4K Retina display, and we wouldn’t have been surprised if Apple had put up the price – but the good news is that the price remains the same, so you can now purchase a Retina iMac for £1,199.

New 21.5in iMac with Retina display: Processor and speed tests

In addition to the Retina display this iMac gains a 3.1GHz quad-core i5 processor, up from 2.9GHz.
There is a 2.3 quad core i7 option for an additional £160.

This processor is a fifth-generation Intel Core Broadwell. Apple decided not to skip ahead to Skylake, despite those sixth-generation processors being available, because the Skylake processors won’t work with the integrated graphics processors that Apple has chosen to drive these models. Apparently this wasn’t an issue with the 27in iMacs as Apple is using the newer Skylake processors in those models – but the 27in iMacs use separate GPUs, rather than integrated GPUs like the 21in iMacs, so that’s likely to explain the challenge Apple faced.

Our colleagues at Macworld US have run Geekbench on the new 3.1GHz 21.5in 4K iMac and found it to be even faster than the 27in 3.3GHz 5K iMac launched this summer (and recently updated). It’s also considerably faster than the 21in iMac model it replaces. These gains are despite the fact that the 4K Retina display will be taking a toll, powering four times as many pixels.

The results were as follows:

Geekbench 3 single-core 64 bit
3.1GHz 21.5in 4K iMac : 3,783
3.3GHz 27in 5K iMac (mid 2015) : 3,691
2.9GHz 21.5in iMac (late 2013) : 3,543
2.7GHz 21.5in iMac (late 2013) : 3,175

Geekbench 3 multi-core 64 bit
3.1GHz 21.5in 4K iMac : 12,799
3.3GHz 27in 5K iMac (mid 2015) : 11,769
2.9GHz 21.5in iMac (late 2013) : 10,683
2.7GHz 21.5in iMac (late 2013) : 10,199

New 21.5in iMac with Retina display: Graphics and speed tests

This iMac features the Intel Iris Pro Graphics 6200 – the same graphics chip is in the 2.8GHz iMac without the Retina display.

In terms of CPU speeds, the new 21.5in iMac can’t quite compete with the older 27in iMacs, though. Which isn’t a big surprise given the fact that the GPU is integrated on the processor in the 21in models and separate in the 27in iMacs. Our colleagues at Macworld US ran Cinebench tests and found that while the new 3.1GHz 21.5in iMac performed better than it’s predecessor, despite the fact that it is driving four times more pixels, but it was left behind by the 5K 3.3GHz iMac that launched in mid 2015.

The results were as follows:

Cinebench R15 CPU
3.1GHz 21.5in 4K iMac : 72 (less is better)
2.9GHz 21.5in iMac (late 2013) 3,543 : 88
2.7GHz 21.5in iMac (late 2013) 3,175 : 100

Cinebench R15 OpenGL
3.1GHz 21.5in 4K iMac : 47
3.3GHz 27in 5K iMac (mid 2015) : 87 (higher is better)
2.9GHz 21.5in iMac (late 2013) : 55
2.7GHz 21.5in iMac (late 2013) : 29.2

Unigine Heaven 1920×1080 OpenGL
3.1GHz 21.5in 4K iMac : 18.5 (higher is better)
2.9GHz 21.5in iMac (late 2013) : 10.6
2.7GHz 21.5in iMac (late 2013) : 7.2

Unigine Heaven 1280×720 OpenGL
3.1GHz 21.5in 4K iMac : 47.3 (higher is better)
2.9GHz 21.5in iMac (late 2013) : 43
2.7GHz 21.5in iMac (late 2013) : 37.2

New 21.5in iMac with Retina display: RAM

The new Mac comes with 8GB RAM and is configurable to 16GB when you purchase it from Apple (you can’t update it later as the RAM is soldered on).  If you choose to opt for the 16GB RAM it will cost an additional £160.

New 21.5in iMac with Retina display: Storage

The 21in Retina iMac has a 1TB hard drive running at 5400rpm, opting for a hard drive if you are used to flash storage will make the Mac feel slow. Luckily there are build to order options that we recommend, although we really think it’s time for Apple to ditch hard drives in favour of Fusion Drives in the iMac line up – Fusion Drives combine a hard drive with faster last storage for the best of both worlds.

We think the best value build to order storage option is the 1TB Fusion Drive, this gives you the best of both worlds, a hard drive for space, and the smaller SSD for quick access of frequently used files and start up information (the SSD in question is only 24GB though, not 128GB as used to be the case). This 1TB Fusion Drive option now costs just £80. We really think that at that price Apple could have thrown it in as standard. Alternatively you can get an even bigger 2TB Fusion Drive for £240.

If you don’t need the space but would love things to be as fast as possible, and you will be frequently accessing large media files, the Flash Storage options will be preferable. There’s a 256GB Flash upgrade for £160 or 512GB for £400.

The flash storage available can take advantage of upgraded storage controllers and 4 lanes of PCI. Apple says this allows them to achieve flash-storage transfer speeds up to 2.5 times those of previous models.

Our advice: avoid the hard drive, if you really need all that storage get an external drive and use that.

New 21.5in iMac with Retina display: Ports

The new iMacs look identical to the old iMacs, the one big change is the addition of Thunderbolt 2 , the previous models were so ancient they only offered the older Thunderbolt 1 ports.

New 21.5in iMac with Retina display: other peripherals

The new iMac ships as standard with the new Magic Mouse 2 (or you can switch it to the Wired Apple Mouse if you prefer).
If you are happy to pay a little more, the new Magic Trackpad 2 costs an additional £44 as a build to order option, or you can get both the Magic Mouse 2 and the Magic Trackpad 2 for £109. In this case you are essentially paying for the Magic Trackpad 2; if you were to buy them separately the new Magic Mouse 2 costs £65 and the Magic Trackpad 2 costs £109 – the mouse is bundled with the iMac so you don’t have to pay for it in this instance.  


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