How much faster is the custom configured White iMac "Core 2 Duo" with a 2.33 GHz processor compared to the stock model? Is it worth the extra cost?

Please note that all models mentioned in this Q&A have been discontinued. The "White" iMac Core 2 Duo systems were replaced by the "Aluminum" iMac Core 2 Duo line.

As noted elsewhere, two of the iMac "Core 2 Duo" models -- the iMac "Core 2 Duo" 2.16 20-Inch and iMac "Core 2 Duo" 2.16 24-Inch -- could have the stock 2.16 GHz "Core 2 Duo" (T7400) processor upgraded at the time of purchase to a 2.33 GHz "Core 2 Duo" (T7600) processor for an additional US$250.

Although it might be tempting to assume that equipped with a 2.33 GHz "Core 2 Duo" processor -- clocked roughly 7.8% faster -- an upgraded iMac "Core 2 Duo" would be faster by a similar margin. However, as the upgraded systems still share the same general architectures, memory, and hard drives, the performance difference is more modest.

In a "First Look", the always reliable MacWorld tested the iMac "Core 2 Duo" 2.16 24-Inch upgraded with a 2.33 GHz processor compared to the stock model, and came to much the same conclusion, noting that:

With a Speedmark score of 259, the beefed up iMac (with 8 percent faster processing cores) was 6 percent faster than the standard configuration 24-inch iMac. More impressive, it was about 2 percent faster than the quad-core 2 GHz Mac Pro in Macworld’s overall system performance benchmark.

Although the results are impressive, particularly compared to the Mac Pro, the 2 GHz Mac Pro is not the stock configuration, but rather the "downgraded" configuration that cost US$300 less. Nevertheless, it is worth noting that the upgraded iMac "Core 2 Duo" 2.16 24-Inch cost US$2249, and the "downgraded" Mac Pro 2.33 GHz cost US$2199. As the iMac "Core 2 Duo" includes an integrated 24-inch display, the iMac is a great value for users who do not need substantial expansion.

In a great post that should be read in its entirety, the always excellent Everything Apple blog also ran the upgraded 2.33 GHz 24-Inch iMac "Core 2 Duo" through a series of tests, including the Cinebench and Geekbench benchmarks and real-world application use -- exporting a DVD chapter to an MPEG4 file using Handbreak, unzipping a file, encoding a video in DivX using Toast 7, and exporting a JPEG with Aperture. The author concluded that the system is a "clear winner".

Ultimately, for most users, the processor upgrade probably did not provide enough of a performance boost to justify a US$250 price increase. However, for those who wanted the fastest iMac available, the upgrade certainly delivered.