The mid-2010 refresh of Apple’s iMac range is more radical than it looks. Although they have the same form factor as their immediate predecessors, under-the-hood component upgrades take the respected all-in-one desktop range to a new level.

As before, there are four off-the-shelf models on offer, with substantial opportunities to customise your machine of choice by ordering through the Apple online store. Two of the new iMacs (including this one) have 21.5-inch screens, with the other two offering massive 27-inch displays.

All iMacs now use Intel’s new Core i-series processors, with the mid-2010 upgrades retiring the ageing Core 2 Duos. Three of the four new iMacs use entry-level Core i3 CPUs, with the most expensive in the line giving you a quad-core Core i5.

If you’re not satisfied with Core i3s, all but the cheapest Core i3 iMacs can be upgraded to dual-core Core i5s, and the top-of-the-range model can be boosted to a Core i7.

Graphics processors have also had a boost, giving up to three times the graphical power of the previous range. The cheapest model on offer, a 3.06GHz Core i3 with a 21.5-inch screen (reviewed here), now has an ATI Radeon HD 4670 graphics processor with 256MB of GDDR3 memory.

This is a significant step up from the previous low-end 21.5-inch model, a 3.06GHz Core 2 Duo, which didn’t have a discrete graphics chip at all.

Instead it relied on an integrated NVIDIA GeForce 9400M. The more expensive 21.5-inch model and cheaper 27-inch version offer ATI Radeon HD 5670 GPUs with 512MB of GDDR3 memory, and the high-end 27-inch iMac gives us an ATI Radeon HD 5750 with 1GB of GDDR5. There are a few minor improvements too.

This model reviewed here, the 3.06GHz 21.5-inch iMac, is the cheapest in the range at £999. It’s only £30 more expensive than the previous entry-level model.

Apple is clearly sticking to its refresh policy of improving internal components while keeping the price points the same, barring small inflationary increases. Its 3.06GHz Core i3 processor has the same clock speed as the previous release’s 3.06GHz Core 2 Duo, but the more modern chip facilitates a significantly-improved performance.

Although the Core i3 processors lack Intel’s Turbo Boost feature, whereby unused cores can be shut down and their power transferred to active cores, they do allow Hyper Threading. This means each of the chip’s two cores can run two threads at once, giving a total of four virtual cores.

The CPU can therefore spread tasks much more efficiently, especially when running multiple applications at the same time.

The 3.06GHz 21.5-inch iMac’s new graphics processor, an ATI Radeon HD 4670, is much faster than the NVIDIA 9400M integrated chipset offered by the previous entry-level iMac. According to Apple, the performance increase offered by this new GPU can reach as high as 50 per cent in some graphics-intensive applications.

Once again, the entry-level iMac has 4GB of onboard memory, arranged in two 2GB SO-DIMM (Small Outline Dual Inline Memory Module) sticks. Its four SO-DIMM slots allow you to upgrade to a maximum of 16GB.

The new iMac uses 1333 MHz DDR3 SDRAM, which is faster than the late 2009 refresh’s 1066 MHz memory. The hard drive is still 500GB, and perhaps surprisingly, there’s no opportunity to upgrade it through Apple’s online customisation options.

This 3.06GHz model is unique in this respect; the other three iMacs can all be upgraded. Note there’s no opportunity to replace or augment your hard drive with a solid state drive either – a customisation option available only on 27-inch iMacs.

Externally, the iMacs haven’t changed since the October 2009 refresh. The screen is still a delicious 16:9-ratio, 21.5-inch IPS display with excellent viewing angles and beautiful, rich colours.

Its 1920×1080 HD resolution has 17 per cent more pixels than most 20-inch displays, and its viewing angles are amazing. You can look at the iMac’s screen from almost any position without the colours shifting at all. Connectivity is still four USB 2.0 ports, a single FireWire 800 socket and built-in Bluetooth 2.1+EDR.

There’s 10/100/1000BASE-T Gigabit Ethernet and WiFi 802.11a/b/g/n for networking, and an SD card reader which is now SDXC-compatible, allowing for a theoretical maximum card capacity of 2TB. It’s bundled with a Bluetooth keyboard with no numerical pad (but you can opt for a full-sized USB keyboard on the Apple online store) and a Magic Mouse.

As you’d expect for a Mac, OS X 10.6: Snow Leopard is preinstalled, as is the latest version of Apple’s popular software suite, iLife.

The new processor and graphics card give the 3.06GHz Core i3 mid-2010 iMac a significant power advantage over most of the late 2009 machines. In our Cinebench rendering tests, using a single core it proved seven per cent faster than its 27-inch, 3.06GHz Core 2 Duo predecessor, but using all available cores, it offered a 33.4 per cent increase.

The Core i3′s Hyper Threading function clearly makes a significant difference. Although an entry-level iMac isn’t an ideal gamer’s machine, it puts in a credible performance here too, running Doom 3 at 132.2 frames per second with the screen resolution set to 1024×768 pixels and the video settings at ultra-high.

Not a massive improvement on the last generation’s 122.8 frames a second, but a step in the right direction.

In our QuickTime encoding test, in which we convert a five-minute test video for use on iPods, the new iMac finished the encoding in 193 seconds, down from 245 seconds with the previous generation. This 22 per cent speed boost will come as welcome news to those who use their Macs for multimedia.

Our iTunes encoding test, where we rip a test CD to iTunes, showed only slight improvement. This is to be expected as the optical drive hasn’t changed, and the speed at which the iMac draws the data from the physical disc has long been the limiting factor in this test.

It’s a pity Apple insists on using a slot-loading 8x SuperDrive (DVD±R DL/DVD±RW/CD-RW) instead of make its peace with Blu-Ray. Even though the Cupertino-based company sees the future of high-definition movies in downloads rather than optical discs, a Blu-ray drive should at least be offered as a custom option, especially given the quality of the screen, which is ideal for HD video.

Another custom option we hoped for, but didn’t get, is an anti-glare screen. All iMacs use a glossy screen, which most users find perfectly acceptable. But some would still prefer a matte display.

Why we’re not given the choice is anyone’s guess. After all, you can opt for an anti-glare screen if you buy a MacBook Pro on the Apple online store.

Most new Mac releases are preceded by rumours and mutterings about what it will offer, some of which prove wildly inaccurate. This mid-2010 iMac refresh is no exception.

It was suggested that next-generation connectivity ports would be included, with USB upgraded to 3.0 and FireWire 1600 introduced. Alas, this was not the case.

Another rumoured new feature was a touchscreen, possibly with iPhone OS integration. Again, this never happened, but keep an eye on the next release of Mac OS.

Back in October 2009, Apple made significant updates to the iMac’s form factor. This mid-2010 refresh is externally identical, but its components have had a major boost.

This is no incremental upgrade. All iMacs now use Core i-series processors, and this entry-level model has a discrete graphics chip, where before it relied on an integrated chipset.

The SD card reader now supports SDXC, and can therefore read cards with a theoretical maximum capacity of 2TB.The screen is still a gorgeous high-definition IPS display.

We liked

The move to the new Core-i processors is very welcome. The Core i3′s Hyper Threading facilities mean the new mid-2010 iMac is great at multitasking, and running applications that use more than one core.

Discrete graphics is very welcome, with the machine’s ATI Radeon HD 4670 adding much to its multimedia and gaming capabilities. The screen is as excellent as ever, and can be viewed from almost any angle without the colours shifting, and iLife remains a very useful software bundle.

Even though the new iMac costs £999, it isn’t overpriced given the quality of its components.

We disliked

The battle between Blu-ray and HD DVD has long been settled in favour of the former, so it’s utterly ridiculous that Apple doesn’t include a Blu-Ray drive in its Mac range.

With no OS-level Blu-ray support, there’s little point in adding your own. We realise Apple feels the future of HD movies lies in downloads rather than optical discs, but surely that’s a decision for the consumers to make?

Many Mac owners have Blu-ray players in their living room. It’s pretty spiteful not to let us watch our Blu-ray movie on our Macs. It’s about time Apple turned its attentions to USB 3.0 too, and maybe offer an anti-glare screen as a customisation option.

Verdict

At a quid shy of a thousand pounds, the entry-level iMac isn’t cheap – but given the quality of the components and performance, it isn’t outrageously expensive either.

The mid-2010 refresh is more than an incremental upgrade. Despite retaining the previous generation’s form factor, the new Core i-series processors and great new graphics capabilities take the iMac a significant step forwards.

Even this, the cheapest entry-level model, offers an excellent performance. It’s a great multimedia machine, a credible (if imperfect) gaming rig and a superb all-round home computer.

Only Apple’s insane refusal to offer a Blu-ray drive and a few omissions like USB 3.0 and an anti-glare screen keep it from near-perfection.

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