Retina 3.3GHz iMac 27in review

When Apple launched the first iMac with Retina display last October (see the full review of the top of the range iMac here), it stood alone in terms of competition from the usual Windows suspects, since no PC maker had anything close in design and performance.

But it was also launched as a solitary model in the Apple catalogue, listed as just one standard configuration, although there was some limited scope to upgrade to better processor, graphics, storage and memory.

Now, as of May 2015, there is an additional off-the-shelf Retina 5K iMac with £400 shaved off the £1,999 price price of the original (now reduced to £1,849). Your £1599 can buy an iMac with the same ultra-high resolution screen and all the usual iMac trimmings, with savings made this time in the main Intel chip, the storage and graphics. (Product code: MF885B/A)

Retina 3.3GHz iMac 27in review: Build and Design

In every respect this is the same iMac with Retina 5K display, using the same chassis with the same formidable build quality, and the same line of ports and connectors along the back.

There’s two Thunderbolt 2 ports for high-speed peripherals and external displays, four USB 3.0, gigabit ethernet, and slot for SD cards up to SDXC specification and a headphone jack.

In place of the 3.5 GHz Intel Core i5 quad-core processor is a slightly slower processor clocked at 3.3 GHz. It’s from the same generation, a Core i5-4590 instead of Core i5-4690. Both chips have separate processor cores on the same die, and include Intel Turbo Boost 2.0 technology which here mildly overclocks up to 3.7 GHz, where the faster processor can reach up to 3.9 GHz.

These are regular four-core chips. In both cases the processor is fixed at working on four threads, in contrast to the mobile-class processors found in most variants of Apple MacBooks, which include Hyper Threading Technology to give the effect of doubling the number of real cores.

The memory quota and specification is the same as before, 8 GB from two 4 GB SO-DIMM modules, and you can easily upgrade this yourself from a removable hatch on the back

In our tests of the main processor we saw close to the same speed as from the 3.5 GHz processor, with benchmark scores around 5-6 percent lower.

From Geekbench 3, the new iMac with 5K Retina scored 3699 points with one core, and 11,792 while running four cores. Those figures are around 5 percent lower than the 3877 and 12,418 points from the original iMac 5K.

Cinebench 15 scored the 3.3 GHz iMac with 134 and 515 points for its two modes, this time 6 and 5 percent behind the first model’s scores (143 and 544 points respectively). The earlier version of Cinebench 11.5 reported the same story, dropping 5 and 6 percent (1.64 down to 1.56 points, and 6.15 down to 5.79 points).

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Retina 3.3GHz iMac 27in review: Graphics

At first glance, we have the same graphics processor driving all those 14.7 million pixels with 60 refreshes each second. But there’s something different in the designation, a certain X missing from the end of the device’s name.

Where the first iMac 5K sports an AMD Radeon R9 M290X, the second has an R9 M290. Technical differences between them are not revealed and we’ve asked Apple if it can explain how they are different.

Until we hear more, and based on the tiny measured differences in performance between GPUs, we’d guess it could be something as minor as a difference in the core or memory clock speeds.

Graphics processors can be ‘binned’ by selecting the best silicon from the fabrication process at time of manufacture, and setting these parts to run with the highest clock speeds. Those parts that don’t work with stability at the top speeds are set at slower clock speeds, and used in lesser graphics cards.

We hope to update this review when we learn officially what the X factor means to the specification of this iMac graphics processor.

As with Intel processor performance, the change of graphics processor see a small drop in the results we measured from the original 3.5 GHz iMac 5K. Batman: Arkham City at 1920 x 1080 pixels and High detail still played perfectly at 84 frames per second, where first model managed 89 fps.

When pushed to a Retina-mode resolution of 2560 x 1440 however, we saw a more significant drop in framerate, even if 66 instead of 85 fps is still perfectly usable to play the game without visible glitches.

Tomb Raider was strangely faster at full-HD resolution when played on the new 3.3 GHz model, averaging 64 fps against 59 fps, for a nearly 7 percent improvement. But pushed to 2560 x 1440 size again it fell back by 10 percent, hitting 42 fps instead of 46 fps from the original 5K iMac. The Unigine Heaven synthetic game benchmark was similarly around 10 percent down, but still able to play the test at 27 fps even at 2560 x 1440 and Medium detail.

Cinebench’s OpenGL test pushes the graphics processor while rendering an animated car-chase scene, and here the new iMac was just 1.4 percent behind the original in version 15 (90.4 versus 91.7 fps); and again we saw an anomaly where the non-X-rated iMac turned in a higher score in the older 11.5 benchmark (56.3 beating 45.1 fps, for a 20 percent better score in the cheaper Mac).

Retina 3.3GHz iMac 27in review: Storage

As standard the original iMac with 5K Retina display comes with a 1 TB Fusion Drive, a hybrid flash and disk system that works seamlessly to give you most of the benefits of a fast solid-state drive, and the bulk capacity of a traditional hard disk.

The new entry-level version is equipped with just a simple 1 TB disk, which does make this model feel slower in general use. Start-up time is lengthened , even if this yardstick from the Windows PC world is almost insignificant here since Macs excel at sleep mode; and don’t demand restarting every Tuesday to apply weekly security patches from Microsoft. But there is some inevitable lag in the system interface, noticeable when applications take a few more bounces in the Dock before they launch.

The Seagate hard disk inside this new iMac is quite fast though as disk technology can allow. With the drive nearly empty, it could reach sequential speeds up to around 210 MB/s (with reads and writes effectively the same speed); the drag really starts to show when multiple demands are made upon the disk drive, and in small-file random read/write speeds. Averaged with data from 4 kB to 1024 kB, we saw speeds of around just 30 MB/s.

Compare this to the PCIe-attached flash drives in other Macs, which would average around 300 MB/s in the same latter test – a ten-fold difference in speed, which would be even marked when the queue-depth (number of paralleled storage I/O operations) is increased.

That’s not to say the disk-only iMac is too retarded to use comfortably. However if you’re used to using a MacBook Air, for instance, you may find a disk-based iMac even with its 3.3 GHz quad-core processor may feel subjectively a little slower in daily use.

Retina 3.3GHz iMac 27in review: Verdict

For a pound under £2000 the first iMac with 5K Retina display actually offers decent value, especially with nothing like it to compare, short of gaffa-taping a 4K UHD display onto a Windows tower PC. The new entry version undercuts it by a useful £250, bringing only around 5 percent slower application and 10 percent graphics performance. It does lose out with the slow disk-only storage though, so you might like to consider configuring it with a Fusion Drive or pure 256 GB flash drive, either option adding £160 to the price.

Here's our preview of the new Retina iMac

There’s a new iMac with Retina 5K display, with a 3.3GHz processor and AMD Radeon R9 M290, starting at £1,599, that’s £400 less than it used to cost to buy a Retina iMac.

This new iMac actually replaces the top of the range non-Retina iMac, which previously offered a 3.4GHz processor. According to reports customers who had purchased that Mac are taking delivery of the new Retina version, which is the same price.

The non-Retina iMacs, with the exception of the £899 model that was introduced in early 2014, haven’t been updated since September 2013.

Read our Which Mac Buying Guide

Retina 3.3GHz iMac 27in review: Price & Specs

The new 27in Retina MacBook offers a 3.3GHz quad-core Intel Core i5 processor, 8GB RAM, 1TB hard drive and AMD Radeon R9 M290. It costs £1,599.

The identically priced 15in MacBook Pro comes with a 2.2GHz quad-core Intel Core i7 processor, 16GB RAM, 256GB Flash storage and Intel Iris Pro Graphics.

While the iMac the processor has a faster clock speed than the MacBook(3.3GHz), it is an i5 chip compared to the MacBook’s i7, and it also ships with a hard drive, which will make that model slower than the flash equipped MacBook.

Incidentally, the top of the range Retina iMac with its 3.5GHz processor and 1TB Fusion drive now costs less than the top of the range MacBook Pro, at £1,849 compared to £1,999. You can read our review of the flagship Retina iMac here.

Retina 3.3GHz iMac 27in review: Processor

The new 3.3GHz iMac with Retina display comes with a 3.3GHz quad-core Intel Core i5 processor (the original Retina iMac with its 3.5GHz processor is still available, now at the lower price of £1,849).

The iMac it replaces offered a 3.4GHz quad-core Intel Core i5 processor, so this new Retina iMac is likely to run slightly slower than its predecessor, but it does at least offer the Retina display to justify its price.

Not only is the processor running at a slower clock-speed, it is the same Haswell processor as has run in the iMacs since 2013. These new Retina iMac features Intel’s Haswell processors – not the newer Broadwell chips that everyone was expecting, suggesting Apple has skipped the much delayed Broadwell processors and is waiting for the next generation, codenamed Skylake.

Probably Broadwell wouldn’t have made a great deal of improvement to older models, it is quite a minor processor boost. Another reason why Apple has skipped Broadwell is the fact that the quad-core Broadwell chips that Apple would have required for the 27in iMac models (and the 15in MacBook Pro models that were also introduced) haven’t yet launched.

All eyes will be on Intel now, 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 or we will have a long wait for faster iMacs.

In the meantime, is Apple likely to skip Broadwell in the 21in iMacs, untouched since September 2013. Could we see Skylake iMacs in September or October?

Retina 3.3GHz iMac 27in review: Speed tests

We haven’t been able to fully test this new model yet, but in our lab tests of the 2013 27-inch iMac with 3.2GHz processor we found it scored 11,261 points in Geekbench 3, or 3541 points with a single core, so we expect to see better scores in the 3.3GHz model.

Retina 3.3GHz iMac 27in review: Storage

The storage is the one area where iMacs are let down – with the exception of the flagship Retina model, which ships as standard with a Fusion Drive (flash and hard drive combo). The problem with hard drives is that they are slower. A flash equipped computer can feel faster than a more powerful computer simply because it can quickly access data from its flash drive.

For example, we reviewed the entry-level iMac with the Fusion Drive (which combines a hard drive and a flash drive) and found that it was faster than the next model up, despite a leap from 1.4GHz to 2.7GHz. For that reason, we recommend that anyone purchasing an iMac spends £200 more on purchasing a Fusion Drive. It can make more difference to the speed of the machine than a faster processor. Read our review of the iMac with Fusion Drive here.

Retina 3.3GHz iMac 27in review: Graphics

The new iMac with Retina display offers an AMD Radeon R9 M290 graphics (this chip is slightly different to the AMD Radeon R9 M290X in the flagship Retina model). The model this iMac replaces (the 3.4GHz version) offered a NVIDIA GeForce GT 775M graphics card.

When we tested the 3.2 27-inch iMac with the NVIDIA GeForce GT 755M we found that it proved quite game friendly, with the kind of graphics horsepower that we thought would make it a good choices for creative professionals using software such as Adobe Creative Suite software and Apple Final Cut Pro.

On that older iMac, at a default 1600 x 900 pixels and High detail, we saw an average of 61 fps playing the Batmark. At full-HD resolution and Medium, it managed 51 fps, while using screen-native resolution of 2560 x 1440 the iMac still allowed a very playable 42 fps, and a minimum framerate here that didn’t dip below 31 fps.

We expect the new graphics card to perform even better, it has been chosen because it needs to be able to powers the Retina screen, there are 14,745,600 pixels to coordinate – and additionally up to one more connected 4K display – so it must be capable of delivering enormous amounts of graphics data bandwidth.

Retina 3.3GHz iMac 27in review: Display

The new iMac with Retina display is identical to that of the Retina iMac introduced in October 2014. It offers a resolution of 5120 x 2880 - that’s 67 percent more pixels than a 4K display.

Impressive to the naked eye, the display of the iMac Retina 5K we tested last year turned in some of the best numbers our humble Spyder4Elite colorimeter has ever measured.

That display was found to have a full 100 percent coverage of the basic sRGB colour gamut. Even IPS display technology often falters here and struggles to achieve even 90 percent coverage.And from the Adobe RGB colour space, the iMac recorded 78 percent cover.

Full brightness from this panel was at 445 cd/m^2. And at its full output it also gave the highest contrast ratio we’ve measured in the standard chequerboard test, returning a figure of 1160:1.

In our colour accuracy test of the top of the range Retina model, we saw an overall average of 1.66 Delta E, a terrific result.

Retina 3.3GHz iMac 27in review: Ports

Like the top of the range Retina iMac, the new Retina model offers two Thunderbolt 2 ports. Thunderbolt 2 doesn’t deliver any more net speed than the original Thunderbolt port. But it does conveniently bond two existing 10 Gb/s full-duplex channels within each cable into a single high-speed 20 Gb/s line. All the other iMacs are stuck with Thunderbolt 1.

Retina 3.3GHz iMac 27in review: Build to order options

The 3.3GHz Retina iMac has the following build-to-order options:

  • 16GB RAM, £160
  • 32GB RAM, £480
  • 3TB hard drive, £120
  • 1TB Fusion Drive £160
  • 3TB Fusion Drive £280
  • 256GB Flash storage £160
  • 512GB Flash storage £400
  • 1TB Flash storage £800

Read more iMac reviews here.

OUR VERDICT

For a pound under £2000 the first iMac with 5K Retina display actually offers decent value, especially with nothing like it to compare, short of gaffa-taping a 4K UHD display onto a Windows tower PC. The new entry version undercuts it by a useful £250, bringing only around 5 percent slower application and 10 percent graphics performance. It does lose out with the slow disk-only storage though, so you might like to consider configuring it with a Fusion Drive or pure 256 GB flash drive, either option adding £160 to the price.

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