While the standard-configuration models of Apple's iMac offer impressive performance, if you choose a couple of build-to-order (BTO) options, you can have the fastest Mac to date that you can order from Apple--a 27-inch iMac with a 3.4GHz Core i7 quad-core processor and a 256GB SSD.

This ultimate iMac is a BTO model that takes the top-of-the-line standard configuration iMac--a £1,649 27-inch 3.1GHz Core i5 quad-core model with a 1TB 7200-rpm hard drive--and replaces the processor and hard drive. The upgrade to a 3.4GHz Core i7 adds £160 to the price. And the 256GB SSD is an extra £400.

The previous Speedmark 6.5 record holder was a build-to-order Mac Pro with a 3.33GHz Xeon Westmere six-core processor, 8GB of RAM, and a price of £3,322. Add a 27-inch Apple LED Cinema Display and the price jumps to £4,240.

We took our previously tested BTO 27-inch 3.4GHz Core i7 iMac with a 1TB hard drive and 4GB of RAM (£1,809) and popped in the SSD from our BTO 21.5-inch 2.7GHz Core i5 iMac. (I say that like its easy, but as I've pointed out in a previous article, opening up an aluminum iMac and installing components is not for something you want to enter into lightly.) Once the SSD was installed, the 27-inch 3.4GHz Core i7 iMac with SSD was simply on fire--figuratively--besting the previous Speedmark 6.5 performance record holder in 14 of the 17 individual tasks that make up our test suite.

The only tests where the ultimate iMac failed to outperform the Mac Pro were with processor-intensive tasks, where applications that can take advantage of the extra cores found in the Mac Pro benefit. Using Hyper-Threading, the Mac Pro was able to present itself as a 12-core system to applications like Handbrake, Cinebench, and MathematicaMark--the iMac maxed out with eight virtual cores. The Mac Pro is 13 percent faster in Handbrake, 21 percent faster in CineBench CPU, and 28 percent faster in MathematicaMark.

Looking at the results of the 3.4GHz Core i7 iMac with and without an SSD, we see that the SSD-equipped system is 18 percent faster overall. With the SSD, duplicating a 1GB file in the Finder is 35 percent faster; uncompressing a zipped folder is 44 percent faster; opening a Word document in Pages is 17.5 percent faster; and an iPhoto file import is more than twice as fast. Differences in processor and graphics scores were understandably insignificant.

When comparing the 27-inch 3.4GHz Core i7 iMac with SSD to the BTO 21.5-inch 2.7GHz Core i5 iMac with SSD, the 3.4GHz Core i7 iMac is 16 percent faster overall. File duplication and uncompressing zipped archive results are identical. Our file compression, Pages, and iMovie export tests are all a couple of seconds faster on the 3.4GHz Core i7 iMac. The biggest differences between these two systems are in processor-intensive tests such as Handbrake, Cinebench CPU, and MathematicaMark, where the Core i7 with Hyper-Threading in the 27-inch iMac is 30, 37.5, and 41.5 percent faster, respectively, than the Core i5 without Hyper Threading in the 21.5-inch model.

You can see a complete list of Speedmark 6.5 results, which includes all of the current Mac models, as well as several older models.