First Look: Macworld Lab: Core changes boost iMac's speed

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When unveiling the Core 2 Duo processor in July, Intel CEO Paul Otellini said that the next-generation Core Duo chip would deliver a 20 percent increase in laptop performance. Apple’s newly unveiled iMacs—which use the mobile version of the Core 2 Duo touted by Otellini—don’t quite approach that performance gain. But they do handily beat out the previous iMac Core Duo models, posting a 10 percent improvement in Macworld Lab’s Speedmark test.

Apple updated its iMac line earlier this week, replacing the dual-core chips with new Intel Core 2 Duo processors. Four models now make up the iMac line: a 1.83GHz 17-inch iMac, a second 17-inch iMac with a 2GHz chip, a 2.16GHz 20-inch model, and a 2.16GHz configuration with a 24-inch screen.

To date, Macworld has received two of these all-in-one systems: the 17-inch 2GHz model and the 2.16GHz 20-inch offering. We’re expecting the new 24-inch and 1.83GHz 17-inch models next week. Until then, we have the test results for the two middle models, which are impressive.

With very similar processor clock speeds as well as identical graphics, RAM, and bus speeds specifications as the Core Duo iMacs released back in January, you may not anticipate much of a performance difference—you’d be wrong. The improvements the Core 2 Duo chip brings to the new iMacs include 4MBs of shared L2 cache—twice that of its predecessors. The new chip also delivers improvements in efficiency and performance when executing instructions. A quick scan of the test results points out just how important these changes are to overall system performance.

Core 2 Duo iMac Benchmarks

Speedmark 4.5 Adobe Photoshop CS2 Cinema 4D XL 9.5.21 Compressor 2.1 iMovie 6.0.1 iTunes 6.0.4 Unreal Tournament 2004 Finder
17-inch iMac Core 2 Duo/2GHz 232 2:04 1:06 2:50 0:57 1:03 65.5 2:34
20-inch iMac Core 2 Duo/2.16GHz 245 1:55 1:01 2:37 0:52 1:03 74.4 2:22
20-inch iMac Core Duo/2GHz 210 2:31 1:11 3:21 1:03 1:26 54.1 2:34
Mac Pro 2.66GHz (Standard) 299 1:25 0:28 1:47 0:38 0:48 91.3 2:01
>Better <Better <Better <Better <Better <Better >Better <Better

Best results in bold. Reference system in italics .

Speedmark 4.5 scores are relative to those of a 1.25GHz Mac mini, which is assigned a score of 100. Adobe Photoshop, Cinema 4D XL, iMovie, iTunes, and Finder scores are in minutes:seconds. All systems were running Mac OS X 10.4.7 with 1GB of RAM, with processor performance set to Highest in the Energy Saver preference pane when applicable. The Photoshop Suite test is a set of 14 scripted tasks using a 50MB file. Photoshop’s memory was set to 70 percent and History was set to Minimum. We recorded how long it took to render a scene in Cinema 4D XL. We used Compressor to encode a 6minute:26second DV file using the DVD: Fastest Encode 120 minutes - 4:3 setting. In iMovie, we applied the Aged video effect to a 1-minute movie. We converted 45 minutes of AAC audio files to MP3 using iTunes’ High Quality setting. We used Unreal Tournament 2004’s Antalus Botmatch average-frames-per-second score; we tested at a resolution of 1,024 by 768 pixels at the Maximum setting with both audio and graphics enabled. We created a Zip archive in the Finder from a 1GB folder.—Macworld Lab testing by James Galbraith and Jerry Jung

Comparing the results of the new 2GHz 17-inch iMac to the old 20-inch 2GHz model, the iMac with Core 2 Duo processor earned a Speedmark score of 232. That’s a 10 percent improvement on the 210 score turned in by the older system. Likewise, most of the individual application tests run on the new iMac showed gains of 10 to 20 percent over the Core Duo iMac. The 2.16GHz iMac bested its fellow Core 2 Duo desktop, the 17-inch, 2GHz model, in all but the iTunes MP3 encode test, where both new systems turned in the same score.

More significant, the 2.16GHz system narrowed the performance gap between iMac and Mac Pro product lines. With twice the number of processor cores, all running faster than the iMac, the Mac Pro had a definite advantage in this match up. But because not all applications and tasks take full advantage of the Mac multiprocessing capabilities, most results showed the Mac Pro between 20 and 30 percent faster than the 2.16GHz iMac. I expect that test results of the new 24-inch model—with its faster graphics and the optional 2.33GHz processor upgrade—could close this performance gap even further.

Stay tuned for more results as we receive our new iMacs as well as Macworld ’s full review of these new systems.

[ James Galbraith is director of Macworld Lab. ]

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