Apple 21.5in iMac (3.6GHz, 4-core, 2019) full review

In 2018 the iMac turned twenty years old and we secretly hoped that Apple would mark the occasion by updating its iconic all-in-one desktop Mac with a brand-new look. Apple was shrinking the bezels on the iPhone, iPad Pro, MacBook Air, so, we thought it was high time that did the same with the iMac.

We’d love to be starting this review with a celebration of a new-look iMac for the 2019, but unfortunately the 2019 iMac looks just the same as it did back in 2012 when Apple slimmed down the aluminium iMac that was first introduced in 2007. It’s the longest Apple has gone without giving a Mac a design refresh.

However, there are changes to the processor, graphics card options and the RAM. We’ll look at these in more detail below. But, suffice to say, they do mean that the 2019 iMac is a much more powerful machine than its 2017 equivalent was. And, chances are, what matters to you is how well your Mac stands up to the demands of modern-day apps rather than whether it looks ultra-modern.

In this review we are looking at the top of the range 21.5in iMac, with its 3.0GHz 6-core 8th generation i5 processor. (We have a separate review for the 27in iMac which has the same processor but a different graphics card).


iMac prices

The 2019 iMac pricing remains the same, in fact, pricing hasn’t changed in the UK since October 2016.

Here's how the pricing of the 21.5in iMac breaks down:

  • 2.3GHz dual-core 7th-gen i5, 1TB hard drive, 8GB 2133MHz RAM, Iris Plus 640, £1,049/$1,099 (note: this is a 2017 model)
  • 3.6GHz quad-core 8th-gen i3, Retina 4K, 1TB hard drive, 8GB 2400MHz RAM, Radeon Pro 555X, £1,249/$1,299
  • 3.0GHz 6-core 8th-gen i5, Retina 4K, 1TB Fusion drive, 8GB 2666MHz RAM, Radeon Pro 560X, £1,449/$1499

BTO options:

  • 3.2GHz 6-core 8th-gen i7 processor + £180
  • 16GB RAM + £180
  • 32GB RAM + £540
  • 256GB SSD + £90
  • 512GB SSD + £270
  • 1TB SSD + £630

It would have been very un-Apple to drop the price of the iMac, so that’s no real surprise and keeping prices the same is good. However, we do feel that the company is cheating consumers a bit by leaving the price of the entry-level model, which lacks the 4K display and hasn’t been updated since 2017, unchanged.

This is a little like the way Apple left the old MacBook Air model in the line up when it updated the Air in 2018. Despite having 5th-gen processors from 2015, that Air still costs £949/$999.

We think the only real purpose of these entry-level models is to be unattractive choices that Apple can up-sell from. We’d strongly advise anyone considering the 2.3GHz non-Retina iMac to spend an extra £200 to get the newer model because it has so much more to offer.

If you are looking for a budget Mac then you might want to consider the Mac mini (reviewed here), or you could look on Apple’s refurbished store for discounted Macs. We also round up the best iMac deals of the week here.

You can buy the new iMac from Apple here.

Design & Build

We are disappointed that the iMac design hasn’t changed in all these years. We expect Apple to take a lead in design and not leave something looking the same for a decade.

Then again, we’re not asking for change for change’s sake. It’s still a good-looking machine so somehow doesn't look dated after all these years, but the design does have its faults.

We, like many others, have to position our iMac on top of a hard backed book in order to have the screen at an ergonomically-friendly height. The inability to adjust the height of the screen, beyond tilting it to face upwards or downwards, is frustrating. This is the main request from many users.

The screen is surrounded by inch-wide bezels and at the bottom there’s a 2.5in aluminium section. We’d love to see Apple slim the bezels down to accommodate a larger display. If you measure the entire screen diagonally it’s 24in so there’s potential for the iMac display to go up to 24in without getting much bigger. For now, if you want a bigger screen then the 27in is the iMac to choose and that's quite a jump.

Big bezels iMac

Read about what we expect from the 2020 iMac here.


We’ve talked about the design of the screen but there is more to the screen than how it looks.

The display is one of the biggest differences between the entry-level 2.3GHz iMac and the other 21.5in iMacs. Back in 2015 Apple added a 4K Retina display to the 21.5in iMac. Since then the 21.5in Retina iMac has offered 4,096 x 2,304 pixels compared to 1,920 x 1,080 on the entry-level iMac.

There were some additional changes to the Retina display in 2017 that made that display a vast improvement to the display that preceded it. In addition to all those pixels, the 2017 and now 2019 Retina displays also offer 500nits and 10-bit dithering. This basically means that they are 43 per cent brighter than previous models, and capable of reproducing 1 billion colours, compared to millions of colours on the 2.3GHz iMac.

So, the screen is a good reason to update if your existing Retina iMac is from 2015. And if you are using a non-Retina screen currently, then prepare to be astonished, but it's no different if you have a 2017 model.

iMac 21.5in

Specs & Performance

As we’ve established above, the only changes to the 2019 iMac are on the inside. Namely a range of new processors, better graphics cards, and faster RAM - at least on the 3.0GHz 6-core option.

We’ll look at the various components below, starting with the processor.


The new 2019 21.5in iMacs benefit from 8th-generation Coffee Lake Intel processors. This is is an upgrade from the 7th-generation Kaby Lake processors in the 2017 iMacs.

One of the biggest advantages of Coffee Lake compared to Kaby Lake is the leap in terms of the number of cores. For the first time there is a 6-core option on the 21.5in iMac. It’s this 3GHz 6-core machine that we are testing here, the alternative is a 3.6GHz quad-core iMac. (That’s six 3GHz cores versus four 3.6GHz cores).

The quad-core option comes at a slightly more attractive price of £1,249, but it has some limitations in comparison to the 6-core model. The processor is an i3, rather than an i5, which means that it isn’t able to Turbo Boost (an Intel technology that enables the processor to accelerate - or overclock - when high performance is required). As a result, when Turbo Boost kicks in, the 3.0GHz 6-core iMac can actually achieve 4.1GHz.

The extra processing cores will be an advantage if you work with demanding apps, such as video, audio and imaging software.

You might recognise these processors from the 2018 Mac mini as they are the same. The 2018 Mac mini has the disadvantage of integrated graphics and the advantage of faster flash storage, though.

The processors inside the 2019 21.5in iMac are as follows:

  • 3.6GHz quad-core Core i3-8100 (same as the £799/$799 2018 Mac mini.)
  • 3.0GHz 6-core 8th-gen Core i5-8500 (same as the £1,099/$1,099 2018 Mac mini.)
  • 3.2GHz 6-core 8th-gen Core i7-8700 (BTO) (same as the £1,249/$1,299 BTO 2018 Mac mini.)

In the 27in line up you’ll find a 9th generation i5 and i9 option, these are from the Coffee Lake Refresh. Find out more about that in our other review.

We’ve run benchmarks on the new iMacs to see just what a difference there is compared to the 2017 generation. Back then we reviewed the 3.4GHz quad-core, 21.5in iMac, with the Radeon Pro 560 graphics. Like the machine we are looking at this time around, that was the top of the range 21.5in model.

In the Geekbench single core test we saw gains over the 2017 3.4GHz model, with the older model having scored 4,894 compared to 5,372. That’s despite the individual cores having a slower clock speed this time round. As you’d expect the multi-core score was significantly higher for the 2019 model. It’s important to note that those scores were using a slightly older Geekbench, and that those Macs were running Sierra as opposed to Mojave. However, even with these discrepancies, the difference is clear.

Another interesting comparison is with the 27in iMac that we have also been testing. Both iMacs have exactly the same processor so, as expected the Geekbench scores were very similar, although the 27in model did see a marginally better result in the multi-core test.

We also have the scores for the 3.2GHz 6-core built to order option on the Mac mini, and the 3.6GHz quad-core Mac mini. This is an interesting comparison because the Mac mini has a SSD and its higher scores certainly seem to indicate that the SSD makes a considerable difference.

What this tells us is that you will see a decent speed bump from the 2017 to the 2019 iMacs, but that choosing an SSD instead of a Fusion Drive is likely to improve things as well, we’ll talk more about the storage options below.


The other major change inside the 2019 iMac is the graphics card. Here we see a boost from the the Radeon Pro 555 with 2GB video memory in 2017’s £1,249 model to a Radeon Pro 555X with 2GB memory in the 2019 model, and a boost from the Radeon Pro 560 with 4GB in the 2017 model to the Radeon Pro 560X with 4GB in the 2019 model.

Graphics capabilities is a big differentiator between the Retina and non-Retina iMac models. The older entry-level model has an Intel Iris Plus Graphics 640 integrated into the CPU so it doesn’t have its own memory. Back in 2015 all the 21.5in iMacs, even the top of the range, 4K iMac, featured Intel Iris Pro Graphics 6200. Now all but the entry level iMac have discrete Radeon Pro graphics cards. So, if you are upgrading from a pre-2015 iMac you will benefit greatly.

We ran the Geekbench graphics tests and we did see some interesting differences between the graphics cards used in the otherwise identically specced 3.0GHz 21.5in and 27in iMacs.

We also ran the Unigene Valley benchmark, and we have comparable scores from other Macs (although it’s worth noting that these benchmarks were performed in older versions of macOS).

This is where you can really see the difference between the iMac with its discrete graphics and Mac mini and its integrated graphics. The scores leave the Mac mini for dust.

If you are running graphics intensive apps then these discrete graphics options are a significant benefit of the iMac range when compared to the Mac mini and the 13in MacBook Pro as both offer only integrated graphics. Incidentally, the 2018 15in MacBook Pro offers the exact same discrete graphics options as the new 21.5in iMacs, although in that case the Radeon Pro 555X comes with 4GB of memory rather than 2GB.

iMac 21.5in


There’s one final change between the 2017 and 2019 models. Apple has tweaked the RAM from 2400MHz to 2666MHz, but only in the top of the range, 3.0GHz 21.5in model. The faster RAM will speed up operations and transfer data quicker.

The main factor against the 21.5in iMac is that the RAM isn’t easily upgradable (on the 27in iMac there is a hatch that can be opened so that new RAM can be added).

Officially the RAM inside the 21.5in iMac can’t be updated, but that’s not entirely true. Regarding the 2017 iMac, iFixIt noted the RAM was located in a hatch behind the logic board, rather than soldered onto the motherboard as was the case previously. So the RAM is accessible, but it’s not something we’d recommend trying at home (and it would void your warranty if you did). We assume that the situation is the same in 2019 and that Apple hasn’t decided to solder the RAM in place.


The storage options haven’t changed and that’s a disappointment because they are one of the biggest disadvantages of the iMac range.

A 1TB hard drive is still the standard option for the entry-level 2.3GHz iMac and the mid-range model. Some people might feel that they need 1TB of storage, however, it’s our opinion that probably you don’t need 1TB of storage so much that it justifies being lumbered with a 5400-rpm hard drive. This will somewhat undo all the good work of the other components inside the iMac so avoid a model with a traditional hard drive.

Luckily you do have options. If you are really convinced that you need 1TB of storage then Apple offers a Fusion Drive, which combines a 1TB hard drive with a small amount of flash storage. As the name suggests, this gives you the best of both worlds in as much as your Mac can store some data in the flash memory, which will speed things up a bit because accessing it will be almost instantaneous.

You can add a Fusion Drive as a build to order option for the 3.6GHz quad-core iMac for £90/$100, But we believe the best option is to add an SSD, for example you can choose a 256GB SSD for £180/$200. If you need 1TB of storage get an external drive or use iCloud (2TB costs £6.99/$9.99 a month).

We did run a storage benchmark on the two iMacs we were evaluating. Just look at how much better the SSD performs in the Mac mini compared to the Fusion Drive equipped 2019 iMacs.

It’s worth noting that in 2017 Apple improved the SSD storage, claiming it was 50 percent faster, with write speeds of 3Gbps. So, even if you have an iMac with an SSD from before 2017, you will experience a boost in comparison.

Ports & Peripherals

Again, there is no change here from the 2017 iMac, although if you are upgrading from an earlier model then you’ll be gaining two Thunderbolt 3 ports (which double up as USB Type-C ports).

You will also find four of the older USB-A ports - and given these are now sorely missed from all Apple’s laptops (bar the older MacBook Air), this is definitely a factor in favour of the iMac. It might be old tech, but many of us still have mice, keyboards and other devices that we want to plug in to our Mac. Not to mention the iPhone charger that comes in the box!

Back of 21.5in iMac


We are disappointed that Apple hasn’t given the iMac a new look - it hasn't changed in appearance since 2012. This would be forgivable if the iMac design was perfect, but it isn’t. The wide bezels are a waste of space and the screen can’t be positioned ergonomically apart from the angle.

MacBooks might make up the majority of Apple's Mac sales, but we'd still appreciate some design love for the iMac and so would people that use them every day.

This is an update for those looking for a performance boost and in that respect, the iMac for 2019 is excellent and bring it in-line with the MacBook Pro. Up to six-core Intel processors, faster RAM and better Radeon graphics cards are all welcome additions on the inside. 

It’s a worthy update, but we are hoping for better things next time Apple updates the iMac.

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