Lab tested: 27-inch Core i5 iMac/2.8GHz Quad-Core benchmarks

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If you’ve been following along, you know that the Macworld Lab has been busy testing Apple’s recently updated line of iMacs. We’ve posted benchmarks and analysis on the 21.5-inch 3.06GHz Core i3 iMac and the 21.5 and 27-inch 3.2GHz Core i3 iMacs. Today, we look at the final piece of the iMac puzzle, the 27-inch Quad-Core 2.8GHz Core i5. And while it does grab the title of “Fastest (standard configuration) iMac Ever” from its predecessor, it does so by a narrow margin.

In our overall performance test suite, Speedmark 6, the new $1999 27-inch Quad-Core 2.8GHz Core i5 (with 1TB hard drive, 4GB of RAM, and ATI Radeon HD 5750 with 1GB of video memory) was just under 4 percent faster than the system it replaces, a 27-inch Quad-Core 2.66GHz Core i5 iMac ( ), with 1TB hard drive, 4GB of RAM, and ATI Radeon 4850 HD with 512MB of video memory.

Results were very similar between the two Quad-Core models, with just a few seconds separating them in most cases. The biggest differences were in the iTunes encode test, with the new Quad-Core 2.8GHz Core i5 model finishing 13 percent faster than the older Quad-Core 2.66GHz Core i5; the HandBrake test, with the new model coming in 26 percent faster; and our Parallels WorldBench tests, with the new model completing the task 21 percent faster. Interestingly, the only test in which the older model prevailed was in our Unzip archive test, which it finished just one second faster than the new iMac.

Looking at the specs between the two models, the biggest difference would appear to be the graphics card. While both use ATI Radeon HD graphics, the new model uses a 5750 with 1GB of GDDR5 memory, while the older model sports a 4850 with 512MB of GDDR3 memory. In our Call of Duty tests, we saw minimal improvement, a little less than 2 percent. For Speedmark, we use a lower 1024 by 768 resolution to allow us to compare the performance of legacy Macs. Unfortunately, this resolution doesn’t always show the benefit of higher-end graphics. When running Call of Duty at the 27-inch iMac’s native 2560 by 1440 resolution, the differences between the two card was much more pronounced. Though both systems slowed down when using the higher resolution, new 2.8GHz iMac still managed a respectable 55.1 frames per second, 35 percent faster than the 40.9 frames per second the 2.66GHz model was able to display.

Comparing the new Quad-Core 2.8GHz Core i5 iMac to the other available 27-inch option, the Dual-Core 3.2GHz Core i3 iMac, the new Quad-Core model was 15 percent faster. As you would expect, the Quad-Core model was fastest in the processor-intensive tasks that can use more than two processors at once, namely MathematicaMark (63 percent faster), Cinebench (29 percent faster), and Compressor (20 percent faster).

Though we don’t yet have the recently announced Mac Pros, we compared the Quad-Core iMac to the currently shipping 2.66GHz Quad-Core Mac Pro ( ) with 3GB of RAM, we see the new iMac was 7 percent faster than the Mac Pro, overall. Though the Mac Pro did better in a few tests such as Cinebench, MathematicaMark and Aperture, it lagged behind in Compressor, iMovie, iTunes, Parallels, HandBrake and iPhoto. The biggest difference was in Call of Duty scores, where the Quad-Core iMac’s frame rate (at 1024-by-768) was 79 percent higher than the Mac Pro’s 49.3 score.

Check back soon for full reviews of all of the new iMacs.

27-inch iMac quad core Core i5/2.8GHz benchmarks

Mark 7
Call of
Duty 4
Finder Parallels
WorldBench 6
27" iMac 2.8GHz
Core i5 quad core
217 0:40 1:09 10.1 5:36 1:47 1:17 0:57 0:58 88.1 0:44 4:03 1:01 0:22
27" iMac 3.2GHz
Core i3
188 0:42 1:37 6.2 6:58 1:59 1:42 1:05 0:59 81.4 0:44 4:45 1:37 0:27
27" iMac
2.66GHz Core i5 quad core
209 0:39 1:12 9.64 5:44 1:50 1:22 1:03 1:07 86.9 0:43 5:07 1:22 0:26
Mac Pro
2.66GHz quad core
203 0:38 1:00 11.13 6:17 1:36 1:09 1:18 1:10 49.3 0:44 4:27 1:15 0:27

Best results in bold. Reference systems in italics.

How we tested. Speedmark 6 scores are relative to those of a 2.13GHz Core 2 Duo MacBook, which is assigned a score of 100 (higher scores are better). Call of Duty score is in frames per second (higher is better). MathematicaMark is a performance score (higher is better). All others are in minutes:seconds (lower is better). The new Core i5 and i3 iMacs were tested with OS X 10.6.4 and 4GB of RAM. The 27-inch 2.66GHz Core i5 iMac was tested with OS X 10.6.2 and 4GB of RAM. The 2.66GHz Mac Pro was tested with OS X 10.6.1 and 3GB of RAM. We duplicated a 1GB file, created a Zip archive in the Finder from the two 1GB files and then unzipped it. We converted 90 minutes of AAC audio files to MP3 using iTunes’ High Quality setting. In iMovie '09, we imported a camera archive and exported it to iTunes using the Mobile Devices setting. We ran a Timedemo at 1024-by-768 with 4X anti-aliasing on in Call of Duty 4. We imported 150 JPEGs into iPhoto '09. 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 used Compressor to encode a .mov file to the application's H.264 for video podcast setting. We ripped a DVD chapter to the hard drive. We recorded how long it took to render a scene with multiprocessors in Cinebench. We ran the Evaluate Notebook test in MathematicaMark 7. We ran the WorldBench 6 multitasking test on a Parallels 5 VM running Windows 7 Professional. We timed the import and thumbnail/preview creation time for 150 photos in Aperture.—Macworld Lab testing by James Galbraith, Mckinley Noble, Blair Hanley Frank, and Chris Holt.

[James Galbraith is Macworld’s lab director.]

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