Apple's professional desktop system, the highly configurable Apple Mac Pro, recently added another choice that features eight processing cores, all running at 3GHz.

Power-hungry computer professionals are always looking for tools to speed up time-consuming tasks. Many hotshots look straight to the top of the line when shopping for a new Mac. Apple's professional tower, the highly configurable Mac Pro, recently added another choice that features eight processing cores, all running at 3GHz.

For software programmers eager to help their applications take advantage of multicore systems, or for Apple Mac users who regularly spend hours compressing video or rendering 3D scenes, purchasing the eight-core Mac Pro makes sense.

Our testing, however, shows that most people would be served just as well by a less-expensive quad-core Apple Mac Pro.

While it's true that processor speeds continue to make modest gains, these days most manufacturers are touting multiple processors on their chips, a change from the past, when processor vendors enjoyed frequent, remarkable leaps in individual processor speeds.

In fact, every Mac in Apple's current product line is using at least dual-core Intel processors - the rest of the Mac Pro processor options feature two dual-core processors running at 2GHz, 2.66GHz or 3GHz. The new eight-core Mac Pro uses two 3GHz quad-core Intel Xeon processors. The problem with this multicore strategy is that throwing more processors at a job doesn't always mean that the task will finish faster.

Aside from the new processor option, the Apple Mac Pro remains unchanged, with four available eSATA hard drive bays; two optical drive bays; 1GB of fully buffered, 667MHz ECC DDR memory (expandable to up to 16GB); four PCI Express card slots; and a choice of three different graphics cards.

Apple claims the number of possible Mac Pro configurations is over 33 million. (We're not inclined to check the maths, so let's just take Apple's word for it.)

In order to try and isolate the performance difference the new processor makes in the Mac Pro, we used Apple's recommended configuration for the most part, but swapped the standard two 2.66GHz dual-core processors (the quad-core option) for two 3GHz quad-core processors (the eight-core option) - a £960 upgrade on the basic two 2.66GHz Dual-Core Intel Xeon setup.

Our eight-core Mac Pro has 1GB of RAM, a 250GB eSATA hard drive, 16X dual layer SuperDrive, and an Nvidia GeForce 7300GT graphics card with 256MB of dedicated video memory.

By using the same configuration on both machines, it is easy to see where and how the different processors impact performance. In the bulk of our testing, in which tasks were performed one at a time, doubling the processors didn't make much of a difference. In fact, the eight-core processor was just 4 percent faster than the quad-core 3GHz Mac Pro in our Speedmark overall system benchmark.

We use Speedmark to test everything from Mac minis to Mac Pros. Some of Speedmark's application tests see no benefit from multiple processors, and some, like our Mac OS X Microsoft Office tests, still rely on Apple's Rosetta translation software to run on the Mac Pro's Intel processors.

One test that did see great improvement with eight processing cores was our 3D-rendering test using Cinema 4D. Running this test, it's easy to see how well this program takes advantage of all of the processors in a system. The rendering window splits itself into eight horizontal chunks, and you can watch each area being drawn simultaneously.

In this test, the eight-core 3GHz system was 44 percent faster than the quad-core 3GHz model, finishing the job in just 14 seconds; the quad took 25 seconds.

The other test that showed measurable improvement, however modest, was encoding a movie using Compressor 3.0.

Running Compressor 3.0 with multiple cores gets complicated. Many of the compression codecs are not optimised for multiprocessing, so to get the best performance, you need to use Apple's Qmaster, a utility included with Final Cut Studio that allows you to set up and share a cluster comprised of your system's internal processor cores.