The 3.06GHz iMac released earlier this week - Apple's first consumer machine to top the 3GHz mark - turned in an impressive performance in our Test Centre, approaching the speed of the standard Mac Pro configuration.

The 24in Apple iMac we've tested is part of the updated iMac line announced Monday by Apple. Externally identical to the aluminum-clad iMacs released in August 2007, these new Macs include a number of under-the-hood improvements, highlighted by the addition of newer Core 2 Duo processors, code-named Penryn. The more energy-efficient Penryn chips also boost the amount of shared L2 cache to 6MB from 4MB in the older iMacs. The new systems also include faster RAM, a speedier frontside bus and - in the case of the 24in Apple iMac - an option to include a more powerful graphics card.

Apple offers three standard iMac configurations: two 20in models that either run on 2.4GHz or 2.66GHz processors (up from 2GHz and 2.4GHz, respectively); and a 24in Apple iMac with a 2.8GHz processor (up from 2.4GHz). Standard hard drive capacities and graphics cards remain unchanged, with the entry-level iMac featuring a 250GB hard drive and ATI HD 2400 GT graphics with 128MB of video RAM. The other two iMacs both feature a 320GB hard drive and ATI HD 2600 Pro graphics with 256MB of video RAM. Despite the changes to the iMac line, pricing remains the same - £799 for the entry-level iMac, £949 for the mid-range model, and £1,149 for the 24in Apple iMac system.

Just as the previous line-up included a faster, optional processor upgrade (in that case, the 2.8GHz Core 2 Extreme) available in a build-to-order configuration, this year's lineup offers a 3.06GHz Core 2 Duo processor, available as an add-on to the standard 24in Apple iMac configuration or in a £1,389 build-to-order system that also features an nVidia GeForce 8800 GS graphics card with 512MB of memory.

In our overall performance testing suite, Speedmark 5, the new entry-level 20in Apple iMac posted a respectable score of 230, about 13 percent faster than last August's 2GHz iMac. The newer system also outperformed its entry-level predecessor in every test except for Quake 4, which was a virtual tie.
However, compared to last year's 20in 2.4GHz iMac, the new machine was 3 percent slower overall, even with the newer Penryn chip. However, a couple of component differences may explain this result - the older 2.4GHz iMac had a larger hard drive and a better graphics card than the new entry-level model; it also costs more than the new system. In that context, then, the Speedmark result isn't that disappointing.

One noteworthy win for the newer 2.4GHz Apple iMac over the older model was in our Compressor Mpeg encoding test. We believe that reflects the new machine's 1,066MHz frontside bus with memory running at 800MHz. The older 2.4GHz iMac had a frontside bus of 800MHz and memory running at 667MHz.

Our build-to-order "ultimate" 24in Apple iMac posted a Speedmark score of 279, just 7 percent slower than the eight-core 2.8GHz Mac Pro. The Mac Pro excelled in the few the applications that can take advantage of more than a couple of processing cores, like Compressor and Cinema 4D, but in other tests (like Photoshop), the custom iMac's faster, processor trumped the more plentiful, multicore (and slower) processors in the high-end Mac Pro.


The customised 24in Apple iMac replaces the standard ATI HD 2600 Pro graphics with 256MB of video RAM with an nVidia GeForce 8880 CS graphics card with 512MB DDR video memory.If you're a gamer, this could be money well spent, as the custom iMac was not only faster than last year's build-to-order iMac at both our Quake 4 and Unreal Tournament game tests, but it also bested the standard configuration Mac Pro as well.