How much faster are the high-end Core i5/Core i7-powered "Late 2009" Aluminum iMac models than the Core 2 Duo powered models? How much faster are these models than the "Early 2009" models replaced?

Please note that all Macs mentioned in this Q&A have been discontinued. The "Late 2009" iMac models were replaced by the "Mid-2010" models on July 27, 2010.

In SPEC CPU2006 benchmark tests, Apple formally reports that the high-end iMac "Core i5" 2.66 27-Inch (Late 2009) custom configured with a 2.8 GHz "Core i7" processor (available for an additional US$200) is 2.4 times faster than the previous high-end iMac model, the iMac "Core 2 Duo" 3.06 24-Inch (Early 2009).

As the Core 2 Duo-powered "Late 2009" iMac models have very similar performance compared to the "Early 2009" models replaced, it would be a safe assumption that the performance difference between the "Late 2009" Core 2 Duo and Core i5/i7 models would be similar. However, the precise performance only can be confirmed by "real world" testing.

Compiling Geekbench benchmarks, the now defunct Timon-Royer blog nicely compiled that the Core i5 and Core i7 models returned results of 7369 and 9638, respectively, compared to 4708 for the iMac "Core 2 Duo" 3.06 24-Inch (Early 2009), a performance difference of roughly 57% and 105%.

The industry-standard MacWorld used the publication's SpeedMark 6 test suite and found:

Comparing the Core i5 iMac's Speedmark 6 scores to its iMac siblings, the Core i5 iMac was 27 percent faster overall than the second fastest iMac we've tested, the recently released 21.5-inch 3.06 GHz Core 2 Duo iMac with 1 TB hard drive and ATI graphics. . .

Our tests of the built-to-order Core i7 iMac (which, other than the processor, has identical specifications as the stock Core i5 iMac) showed even greater performance prowess. With a Speedmark 6 score of 225, the [US]$2199 Core i7 iMac was nearly 8 percent faster than the Core i5 iMac.

The always superb BareFeats ran Cinebench, Geekbench, Compressor and After Effects tests and found that the Core i5 and i7 models were "significantly faster than the fastest dual-core iMacs" and further noted:

The Core i7 (and i5) have "Turbo Boost" which increases the core clock speed when only one or two cores are active. We may have observed that phenom when we ran the single CPU test in Cinebench. In that scenario, the 2.8 GHz Core i7 was 21% faster than the 3.06 GHz Core 2 Duo.

You also may wish to review a variety of real-world Photoshop CS4, After Effect, and Halo tests as well as Geekbench and Cinebench benchmarks from site sponsor Other World Computing that show the performance differences with an extensive number of RAM configurations.

Ultimately, the exact performance difference between the Core i5 and i7 "Late 2009" iMac models and previous and current Core 2 Duo-powered systems depends on the tasks performed, but the performance difference is far more substantial than the price difference. Those who place more emphasis on speed than price likely will find the US$300-US$500 price premium to be money well spent.

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