How much faster are the "Early 2008/Penryn" Aluminum iMac Core 2 Duo models than the original Aluminum models?

Please note that all iMac models mentioned in this Q&A have been discontinued. The "Early 2008/Penryn" iMac models were replaced by the "Early 2009" line on March 3, 2009.

Apple reports that the "Early 2008/Penryn" Aluminum iMac Core 2 Duo models are "up to 28% faster than [the] previous iMac" in a series of real-world tests. Specifically, the high-end iMac "Core 2 Duo" 2.8 24-Inch (Early 2008/Penryn) is 28% faster than the replaced high-end iMac "Core 2 Duo" 2.4 24-Inch (Mid-2007/Aluminum) running an "HDV render and encode" test in Final Cut Pro. Other real-world tests from Apple show the "Early 2008/Penryn" line to be between 17% and 27% faster.

As the "Early 2008/Penryn" systems have faster and more energy-efficient 45 nm "Penryn" processors -- compared to 65 nm "Merom" processors in the original "Aluminum" models -- larger level 2 caches (6 MB compared to 4 MB), faster frontside buses (1066 MHz compared to 800 MHz), and faster memory (PC2-6400 compared to PC2-5300), these test results seem quite reasonable. However, third-party test results always are worthwhile.

Several websites have benchmarked and tested the "Early 2008/Penryn" iMac Core 2 Duo systems, including MacWorld, PC Magazine, and C|Net. All of these reviews and test results should be read in their entirety for the complete perspectives provided by each author, but a helpful clipping from each is provided below for your convenience.

In a "From the Lab" session, MacWorld reported:

In our overall performance testing suite, Speedmark 5, the new entry level iMac posted a respectable score of 230, about 13 percent faster than last August's 2 GHz iMac. . .

However, compared to last year's 20-inch 2.4 GHz 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 2.4 GHz iMac had a larger hard drive and a better graphics card than the new entry-level model; it also cost [US]$300 more than the new system. In that context, then, the Speedmark result isn't that disappointing.

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

Our build-to-order "ultimate" iMac ["Core 2 Duo" 3.06 24-Inch (08)] posted a Speedmark score of 279, just 7 percent slower than the [US]$2,799 8-core 2.8 GHz Mac Pro.

MacWorld also has posted an excellent follow up review which is well worth reading.

C|Net reviewed the "Early 2008/Penryn" iMac models and was impressed by:

A 22-percent increase on our multimedia multitasking benchmark compared with that of last year's model. . . On CineBench 10, a 3D rendering test that taxes the CPU and graphics subsystems, the new iMac outpaced the older 24-inch model by 8 percent, which is about the margin we'd expect between two systems released seven months apart. This iMac's faster frontside bus, faster memory, and larger L2 cache each plays a role in its improved performance over last year's model, as does the new version of Leopard (10.5.2), we suspect.

PC Magazine compared the "Early 2008/Penryn" models to the original Aluminum models running Photoshop and found:

Although the [previous] 20-inch had scored a still-quick 42 seconds running Mac OS X, the latest iMac finished in a mere 34 seconds. In Windows, the [Early 2008/Penryn] 24-inch finished in a blazing 30 seconds, barely half the time it took the older iMac (58 seconds).

Ultimately, due to the modestly faster processors, larger level 2 caches, faster frontside buses, and faster RAM, there is a notable performance difference between the "Early 2008/Penryn" iMac Core 2 Duo models and the line that these systems replaced.

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