iMac Core 2 Duo full review

The iMac was originally conceived as a relatively compact all-in-one computer, and that was a large part of its appeal. Compact, however, is not word most people would use to describe the new 24-inch iMac, which features the latest Apple technology tucked behind a massive flat-panel display. But for people who want a fairly professional system without making the jump to a Mac Pro, the new large-screen iMac fills a tempting middle ground. It gives you impressive performance, but without the expansion options of a professional tower system.

For the rest of the iMac range, Apple has filled out its all-in-one desktop line with models to fit almost every budget and desire for display size and features. The new crop of iMacs replace the 17-inch 1.83GHz Core Duo model and 20-inch 2GHz Core Duo model with new price points designed to appeal to a wide range of buyers.

All models include built-in AirPort Extreme (802.11g standard), wireless networking, mini-DVI video output, an iSight camera, an Apple Remote, three USB 2.0 ports, (plus two USB 1.1 ports on the keyboard) one FireWire 400 port and Gigabit Ethernet plus combo ports for analogue and digital audio input and output (previous iMacs had analogue-only audio input).

The 24-inch iMac is monumental. Its large, widescreen display offers a resolution of 1,920 x 1,200 pixels, the same as Apple’s £779 23-inch Cinema HD Display. And as with Apple’s 23-inch display, the iMac has enough resolution to show off many windows, palettes, and every pixel of full 1080 high-definition video (with some vertical pixels left over for good measure). Compared to the previous largest iMac, the 20-inch model, this one has 30 per cent more pixels.

As with most of Apple’s new displays, the 24-inch iMac isn’t just about gaining more screen real estate. Its display is roughly 43 per cent brighter than the new 20-inch model, with the same 400 candelas per square meter (also called nits) as Apple’s 23-inch and 30-inch displays. Even with the gigantic display, however, the iMac feels sturdy and well balanced. With its thin design, the 24-inch iMac weighs a surprising 24.7 pounds, just 2.7 pounds more than the 20-inch model.

Aside from the gigantic screen, the 24-inch iMac comes with a 2.16GHz Intel Core 2 Duo processor with 4MB of shared L2 cahce (twice that of the previous Core Duo iMac), a 667 frontside bus, 250GB Serial ATA hard drive, an 8x double-layer SuperDrive, and nVidia GeForce 7300 GT graphics with 128MB of GDDR3 memory. In addition, it’s the only iMac to ship with FireWire 800.

Bargain basement

At the other end of the scale is a new entry model, the 17-inch 1.83GHz iMac – this stripped-down model has the same 2MB of shared L2 cache as the previous iMacs, and is the only model to ship without built-in Bluetooth 2.0 wireless networking, an Apple Remote, or a SuperDrive. It’s very similar to the iMac that Apple sells to educational institutions for £639, except that the extra £40 buys you a Core 2 Duo processor instead of Core Duo processor (running at the same speed) and a 160GB Serial ATA (SATA) hard drive instead of an 80GB hard drive. It includes 512MB of 667MHz RAM on two 256MB DIMMs, a 24x combo drive, AirPort Extreme wireless networking, and Intel’s GMA 950 integrated graphics, which borrows the 64MB of RAM it uses from main memory. You may want to spend an extra £50 to get 1GB of RAM (the maximum is 2GB).

Middle of the road

Between these two sit the £799 17-inch 2GHz and £999 20-inch 2.16GHz models, which are nearly identical except for their different processor speeds and display sizes – their screens feature 1,440 x 900 pixel resolution and 1,680 x 1,050-pixel resolution, respectively.

Both have the larger 4MB of shared L2 cache, 250GB SATA hard drives, 8x double-layer SuperDrives, ATI Radeon X1600 graphics with 128MB GDDR3 memory, built-in AirPort Extreme and Bluetooth 2.0 wireless networking, and an Apple Remote. Both models also come with 1GB of 667MHz RAM, split between two 512MB SODIMMs.

It’s great that Apple has made 1GB of RAM the standard on the three high-end models; unfortunately they are all matched pairs rather than single modules. Whereas matched pairs of RAM are essential for the £679 iMac – which improves graphics performance because of its integration with the system RAM – the other iMacs don’t gain anything from having two matched DIMMs instead of one (it does presumably save Apple money, however, because two smaller DIMMs are generally cheaper than one larger one). But for the end user upgrading RAM (up to the maximum of 3GB) requires removing one included DIMM to gain a free RAM slot – making it more expensive and wasteful to upgrade RAM on your own. Also, the Intel chipset that Apple uses in the iMac means the operating system can address only 3GB of RAM, even if you were to put two 2GB DIMMs inside.

Each of the four models has a built-in iSight video camera, Gigabit Ethernet, an Apple Keyboard and Mighty Mouse, three USB 2.0 ports (plus two USB 1.1 ports on the keyboard), two FireWire 400 ports (one 400; one 800 on the 24-inch model), built-in stereo speakers with 12W of digital amplification (24W on the 24-inch model), a built-in microphone, and analogue and digital audio input and output (the previous generation of iMac had analogue-only audio input in addition to analogue and digital audio output).


Performance gains from the new chips are modest compared with the previous Core Duo iMacs. To see how well the new iMacs perform, the Macworld Lab put them through our standard suite of tests. All the new iMacs performed strongly and bested the previous top iMac – the 20-inch 2GHz Core Duo model – in most tests. The 24-inch iMac garnered an impressive Speedmark score of 245, only nine points below the 2GHz Mac Pro (not surprisingly, the 24-inch iMac earned the same Speedmark score as the new 20-inch model, which has the same processor). The 17-inch Core 2 Duo iMac, running at the same processor speed as the old 20-inch model, scored 10 per cent higher in our Speedmark suite, while the 20-inch 2.16GHz Core 2 Duo was 17 per cent better – and both models cost hundreds of pounds less.

And although the 1.83GHz Core 2 Duo iMac clocked eight points behind the previous 2GHz iMac Speedmark score, it beat the older iMac in several tests: it posted a seven per cent speed boost in Apple’s Compressor MPEG-2 encoding test and a 19 per cent faster time in the iTunes MP3 encoding test.

The one area in which the 17-inch 1.83GHz iMac performed significantly worse was in our Unreal Tournament 2004 Frame Rate test. Because this model uses the Intel GMA 950 integrated graphics instead of dedicated high-speed graphics processing, the low-end Mac could process only 21.7 frames per second – 60 per cent fewer than the old iMac, and 67-73 per cent fewer than the other new iMac models. The integrated graphics also caused noticeable differences in Nanosaur 2 (movement seemed less fluid), and opening and closing multiple Finder windows wasn’t nearly as smooth as with the other Core 2 Duo iMacs. However, the 1.83GHz model was able to play HD movie trailers without dropping frames. The other two models have much better frame rates of 65.5 (2GHz) and 74.4 (2.16GHz), which beat the old 20-inch iMac’s 54.1 frames hands down – even though they all use the same ATI Radeon X1600 graphics processor with the same amount of RAM.

All the iMacs were between 9 per cent and 24 per cent faster than the old 20-inch iMac in our Adobe Photoshop CS2 suite of tests, which runs in Rosetta translation because Photoshop isn’t yet an Intel-native application. Even the low-end iMac shaved 14 seconds off the old model’s time of 2 minutes and 31 seconds.

Another big improvement is that the new iMac pumped out more than 25 additional frames per second in our Unreal Tournament test – a nearly 47 per cent boost in frame rate over the 20-inch Core Duo model. The included nVidia graphics chip is good news for anyone who likes to play games. And users interested in the best performance can replace the 7300 GT with the GeForce 7600 GT with 256MB of video memory for an additional £80, making this the first iMac with an option to upgrade to a different graphics processor.

Judging from the test scores, the 24-inch iMac seems to bridge the performance gap between standard iMacs and Mac Pros very well. Compared to the previous high-end iMac – the 20-inch 2GHz Core Duo model – the 24-inch iMac showed a nearly 17 per cent overall Speedmark improvement. Most impressively, our MPEG-2 encoding test using Apple’s Compressor was 28 per cent faster than the old 20-inch model, and the Cinema 4D Render test showed a 14 per cent jump – good numbers for professional-level use.

For general operations, the 24-inch iMac’s overall responsiveness was excellent. Opening, dragging, and resizing windows was very quick. HD video playback was smooth, and working in Intel-native applications such as Final Cut Pro, Motion, iMovie, and iWeb was snappy. (You can custom configure a 24-inch model with a 2.33GHz Core 2 Duo processor for an extra £170. Our benchmark chart shows the performance improvements you’ll see with this faster chip.)

In general, there was very little difference between the 2GHz and 2.16GHz models in terms of hands-on feel – both were snappy and responsive at most tasks. The £679 iMac, however, definitely suffered from its slower processor and smaller amount of RAM: launching applications took a little longer and applying transitions in iMovie was slow, for example. And the greater screen brightness of the 20-inch model was noticeable, but didn’t make a huge difference.

The performance difference between the Core Duo and Core 2 Duo makes these upgrades basically speed bumps rather than completely new iMacs, but Apple is giving you more Mac for less money – which should be applauded. And now that Apple offers several iMac models, you have a better chance of finding one that precisely suits your needs and budget.

Finally, the 24-inch iMac has an upgraded sound system, with a 24W digital amplifier (twice that of the other models) to power the built-in stereo speakers. The sound was much louder than on any other iMac we’ve used – useful for, say, watching a movie from across the room – and it had fairly good quality. (Audiophiles will still probably want a separate set of powered computer speakers or want to connect the iMac’s digital audio output to a good home-theatre system.)

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