It's been two years since Apple last updated the non-Retina versions of the iMac (if you don't include the  cheaper iMac which Apple introduced in June 2014 - now a year old). The big surprise was that Apple has left the non-Retina iMacs untouched, while recently adding a new, cheaper 27in Retina model to its line up. The new Retina model costs £1,599 (the same price as Apple's top of the line non-Retina 27in iMac did previously).

Notably absent from 2014 and 2015’s upgrade cycles (so far) was the rest of the iMac range, with the four original iMacs remaining untouched since they were updated on 24 September 2013. We are still waiting for these iMacs to be updated, and new processors from Intel that could be destined for the iMacs have been shipping for some time. We had hoped that the 21.5in iMac would get an update at WWDC on 8 June, and then at the 9 September event, but no update happened.

Now reports are appearing that suggets Apple will update the iMac range this autumn. In additon, code in the El Capitan beta suggests that the new 21.5in iMac could be getting a 4K Retina display. Read more about El Capitan here: Mac OS X 10.11 El Capitan: expected release date and new features.

Here, we bring you everything you need to know about when Apple will upgrade the iMac range, including the new iMac's specs, features, UK price and expected release date.

To discover what we think about the original Retina 5K iMac, take a look at our Retina iMac review. If you are in the market for a new Mac, read our iMac or Mac mini - Mac desktops compared and Best Mac to buy: Mac Buying Guide. Apple has also introduced new series of 15in MacBook Pro with Retina display but they also lack the newer processors.

Also read: When will Apple update the Mac mini and Everything Apple announced at the iPhone launch

New 21in iMacs launch date

The new 21in iMac with 4K Retina display may not have put in an appearance at the iPhone launch on 9 September, but that doesn’t mean it won’t be arriving soon.

According to a report on DigiTimes, production of the new iMac has already begun and it will be released in November.

This follows claims by KGI Securities analyst Ming-Chi Kuo that the iMac is going to be getting a significant update in the next few months.

Kuo believes Apple will introduce new iMac models in the third quarter. Which would suggest that the update could even come before the end of September.

Kuo notes that the timing would help Apple drive Mac sales growth in the Back to School quarter, notes MacRumors, but it may be the case that Apple has missed the boat there as the launch didn't happen by the end of August.

New 21.5in iMac could offer Retina display

It looks like Apple has plans to improve the display of the 21in iMac – code in an early El Capitan beta suggests that a 4K 21.5in iMac may be in the pipeline.

According to reports, one of the developer betas for OS X 10.11 El Cap included a reference to a Mac with a 4096 x 2304 resolution display – also known as a 4K display. That is smaller than the display on the 27in iMac, which is 5120 by 2880 resolution, while the 15in Retina MacBook Pro offers 2880 by 1800 pixels. Therefore it is likely that this 4K display is destined for the 21.5in iMac. 

Analyst Ming-Chi Kuo also expects the new iMacs to offer better displays. He predicts that the panel will use a "LED phosphor material called KSF to notably boost color saturation".

Yet more evidence has emerged in the El Capitan beta that suggests the 21in iMac is going to get a Retina display.

According to a report on French website Consomac, there are images in the beta that hint at the resolution of a new 21.5-inch iMac with a Retina display. That would be a native resolution of 4096 x 2304, which is just over twice the current resolution of 1920 x 1080.

Is the 21in iMac gains this new high res display it will be possible to watch 4K video on it.

New iMac specs: Price

Another important question is how much will the new iMacs cost if, and when, they do launch?

The current line up is priced as follows:

  • 21.5in, 1.4GHz dual-core i5, £899
  • 21.5in, 2.7GHz quad-core i5, £1,049
  • 21.5in, 2.9GHz quad-core i5, £1,199
  • 27in, 3.2 quad-core i5, £1,449
  • 27in Retina 5K, 3.3 quad-core i5, £1,599
  • 27in, Retina 5K display, 3.5 quad-core i5, £1,849

We expect that Apple won’t change the prices a lot when the new models launch, although it is possible that by gaining Retina displays the 21in iMac range may go up in price. The non-Retina 27in iMac may be discontinued.

How long has it been since Apple updated the iMac?

If you ignore the £899 iMac and the Retina iMac, which were both introduced in 2014, and the recent addition of a new, cheaper, 27in Retina iMac, the last time the iMac saw a proper update was in September 2013 when Apple added the Haswell processor, new graphics, next generation Wi-Fi and faster PCIe flash storage options. Read our review of the 2013 iMacs. You can read all our iMac reviews here.

What features do you think the iMac needs most? Take part in our Poll

Will the new iMac have a Broadwell or Skylake processor?

At the beginning of June, Intel finally announced its quad-core range of Broadwell processors – the ones we were all expecting Apple to use in the new 27in iMacs and 15in Retina MacBook Pro.

Strangely Apple chose to stick with Haswell processors when it announced a new 27in Retina iMac a couple of weeks previously, rather than use the newer Broadwell versions. Many have quesitoned why Apple didn’t just wait a few more weeks? The general consensus is that Apple has skipped Broadwell in favour of Skylake for its high end Macs. Skylake should be here before the end of the year, so we may see a pro-level iMac and MacBook update in October.

But back to the rest of the iMacs, will Apple wait until October to update the rest of the iMac range, or will it update them now with these new Broadwell processors? We think that an update could be immanent. The MacBook Air and the 13in MacBook Pro both use new Broadwell dual core processors, so surely the 21.5in iMac can accept the Broadwell treatment too.

In fact, we think that one reason why Apple rushed out the updates to the 27in Retina iMac models was so that the lack of Broadwell chip wouldn’t be so noticeable when it updates the 21.5in iMac models.

The 21.5in iMacs currently come in three configurations:

  • The entry level 1.4GHz Intel Core i5 Haswell dual-core processor
  • The 2.7GHz Intel Core i5 Haswell quad-core processor
  • And the 2.9GHz Intel Core i5 Haswell quad-core processor

Now that the Broadwell quad-core chips are finally shipping, Apple could update these Macs – as long as the launched chips aren’t intended only for mobile.

Alternatively Apple might wait until later in the year to update all the iMacs to Skylake, but the current iMacs are so old now – nearly two years – so it seems more likely that an update will happen sooner rather than later.

New iMac specs: Graphics card

The current line up of iMacs features the Intel HD Graphics 5000 at the entry-level and the next model up offers Intel Iris Pro Graphics. You can expect to see updates to these cards – the new MacBook Pro 13in offers Intel Iris Graphics 6100, for example, so we’d expect this to appear in the iMacs too.

The higher-end iMacs feature NVIDIA GeForce graphics – the 21.5in iMac offers a GT 750M, the entry-level 27in has a GT 755M and the top of the range (excluding the Retina model) offers a GT 775M. The GeForce 700 series have been around for some time now, first introduced back in May 2013, so they could be described as a bit long in the tooth by now. The GeForce 800 series was introduced in March 2014, so even those graphics cards are now a year old. If Apple is going to stick with NVIDIA then it looks like the GT 900 (introduced in September 2014) might fit the bill. There’s a new GT 1000 series on the horizon, but it’s not expected until 2016.

The iMac with Retina display runs an AMD Radeon R9 M290X processor, so it is feasible that Apple might switch from NVIDIA to AMD, as they have in the past. The company may even move to integrated graphics cards, which are part of the motherboard, but if Apple does this it is likely to upset a lot of pro users.

The El Capitan code also includes a reference to Intel graphics chipset the Iris Pro 6200, which isn’t in any current Macs. It is logical to suppose that this graphics processor (which is integrated in Intel’s Broadwell processors and launched earlier this month) will be finding its way into this future 4K iMac, notes 9to5Mac.

There are also references to four new AMD Radeon R9 processors (M380, M390, M395 and M395X) in the beta, but it’s not clear where these would be destined for.

Will the non-retina 27in iMac be updated?

Like the 21.5in models, the non-Retina 27in iMac model may also get an update this autumn, or, more likely, it may disappear from the line up.

That model currently comes in the following configuration:

  • 3.2GHz Intel Core i5 Haswell quad-core processor

New cheaper Retina iMac launched, price of £1,999 model reduced

Apple first released the 27in Retina 5K iMac in October 2014, alongside the iPad Air 2, iPad mini 3 and a new Mac mini. When it launched the 27in Retina iMac cost £1,999 and offered a 3.5GHz quad-core Intel Core i5 processor, 1TB Fusion Drive and AMD Radeon R9 M290X graphics. The price of this model has now been reduced by £150 to £1,849. Read our preview of the 3.3GHz Retina iMac here.

On 19 May, Apple added a new 27in Retina iMac to it's line up. You can now purchase a 27in iMac with 5K Retina display with a 3.3GHz processor for £1,599.

This new, entry-level model comes with 3.3GHz quad core Intel Core i5 (we were presuming this was a newer Broadwell chip but it turns out that Apple is still using Haswell as the Quad-Core Broadwell still isn't available), 8GB RAM, 1TB hard drive and an AMD Radeon R9 M290 graphics card. It costs £1,599.

In adding this new 3.3GHz Retina iMac, Apple has removed the 3.4GHz non-Retina iMac from the line up, which was also priced at £1,599. Apparently, people who order the non-Retina £1,599 iMac before the recent update are receiving the new Retina version of that Mac, according to a Reddit post, via AppleInsider. 

Previously the only iMac with Retina display offered a 3.5GHz processor, 8GB RAM, and a AMD Radeon R9 M290X graphics card £1,999. It shipped with 1TB Fusion Drive as standard, which gave users the benefit of a faster flash drive to use alongside the hard drive.

The flagship iMac still offers a 3.5GHz quad core Intel Core i5 appears to be unchanged, 8GB RAM, 1TB Fusion Drive and an AMD Radeon R9 M290X graphics card. It now costs £1,849, £150 less than when it was introduced.

New 27in Retina iMac: Why didn't Apple use the Broadwell processor?

The 27in Retina iMac models still feature Intel’s Haswell processors, rather than the newer Broadwell, suggesting Apple is skipping the much delayed Broadwell processors and waiting for Skylake.

While it's possible Broadwell wouldn’t have made a great deal of improvement to the 2014 models, the fact that Apple has skipped that generation of chips will raise eyebrows. 

Unfortunately the quad-core Broadwell chips that Apple would have required for the iMac models (and the new 15in MacBook Pro models that were also introduced) hadn't launched at the time Apple revealed the new updated models. However, just a few weeks later Intel released the quad-core Broadwell chips everyone thought would feature in these Macs. 

All eyes will be on Intel as the company gears up to release Skylake, which is what everyone is really waiting for. Hopefully it won’t take Intel another year to release Quad-core versions of Skylake - we've heard that the new processors could arrive before the end of the year.

Everyone has been waiting for Intel’s Broadwell processor to arrive in the iMac, but the new Intel processors have been delayed to such an extent that it is thought that Apple is now waiting for their successor - Skylake - to launch.

Intel’s new generation of processors, Broadwell, faced major delays. Broadwell uses the 14nm manufacturing process and is said to consume 30% less power than its predecessor Haswell. That should be good news for battery life on the portable Macs, but also for those Macs with especially power hungry screens.

The successor to Broadwell, Skylake is on the horizon, and due to launch before the end of 2015. Skylake will also use the 14nm manufacturing process, but it will bring even greater CPU and GPU performance, along with reduced power consumption. Features of Skylake will include PCI Express 4.0 and Thunderbolt 3.0, which are likely to appear in the Macs that feature those chips.

After Skylake the next round of processors will be Cannonlake, using the 10nm process but don’t expect to see them before 2017.

Read on for more of our predictions of when Apple will update the 21in iMac range.

New iMac specs: storage

We really hope that Apple brings flash storage to the new range of iMacs in the form of a Fusion Drive, like the one added as standard to the Retina 5K iMac.

The current iMac range is crippled somewhat by the slower hard drives that Apple uses. While a hard drive has the benefit of offering more storage – in the case of these iMacs 1TB – it is a lot slower than the flash drives used in all of Apple’s laptops. To the extent that Mac laptops with similar processors will perform better than the equivalent iMac due to the faster SSD drive.

Apple offers a Fusion Drive currently as a £200 build to order option, we think it should be offered as standard in all Apple’s desktops. Alternatively Apple could start to offer flash drives as standard.

New iMac specs: Ports & USB Type-C

Of all the features on the new MacBook, USB Type-C has probably got the most attention - due to the fact that it’s the only port on the MacBook (read why we think the new MacBook doesn’t deserve all the criticism it’s getting).

When that Mac arrived with the single USB Type-C port there was some concern that it might spell the end for Thunberbolt. Given that Apple has strongly promoted this technology, which it describes as “revolutionary I/O technology that supports high-resolution displays and high-performance data devices through a single, compact port,” the company is very unlikely to be planning to drop it, plus as you can see above, Thunderbolt 3.0 is on its way.

The current line up of iMacs features Thunderbolt 1 (with the exception of the Retina iMac which has Thunderbolt 2). Thunderbolt 1 offers 10Gbp/s. Because they weren’t updated in 2014 these iMacs didn’t gain Thunderbolt 2, which offers 20Gbp/s. When it arrives Thunderbolt 3 will offer 40Gbp/s and be able to drive two external 4K displays (or a single external 5K display).

The USB Type-C port is compatible with USB 3.1 and therefore offers 10Gbp/s (double that of USB 3), but it also allows for charging, as it is able to deliver power at up to 100 watts at 20 volts. You are able to charge the MacBook via this port.

However, as yet USB-C only features on the new MacBook. Will it make its way onto the new iMacs? It seems likely that it will, but simply as a replacement for USB 3.0, we definitely don't expect it to replace Thunderbolt.

The current iMac line up offers the following ports and standards:

  • Headphone
  • SDXC card slot
  • Four USB 3 prots
  • Two Thunderbolt ports
  • Ethernet
  • Kensington lock slot  
  • 802.11ac WiFi
  • Bluetooth 4.0

New iMac specs: Design  

Could the design of the new iMacs change in the next generation? The slim unibody of the current style of iMac was introduced in November 2012, prior to that the design hadn’t really changed since 2009 when the Aluminium unibody design in 21.5in and 27in launched. Previous to that the Aluminium iMac launched in 2007 and came in 20in and 24in versions, and back in 2006 Apple launched the Intel iMac with it’s plastic finish, similar in design to the iMac G5 that launched in 2004. Two years prior to that was the lampstand-like iMac G4 in 2002, and in 1998 the original iMac launched.

That’s a change of design every two or three years, so some might think a new look iMac is due. However, we like the look of the current iMac and can’t think of any way it could change for the better, looking back at the generations of iMacs that preceded it, it does look like evolution to this point, we can’t imagine what can follow. Sure it can get thinner, but the weight and dimensions don’t really matter for a desktop machine.

Features some people would like to see probably include an extendable base to the iMac so that you can position it differently – currently it isn’t possible to raise up the iMac for a more ergonomic position. Aside from that people would probably like to see a Retina display come to the rest of the range.

Read our: 2014 iMac with Fusion Drive review and 2014 budget iMac review as well as our iMac Retina review and the review of the 2013 iMacs.