Product Reviews

With the Power Mac G5 now upon us, the G4 is starting to look decidedly sluggish. Perhaps it's time for an upgrade. Fortunately, with such massive, sudden demand for anything that will breathe new life into an ailing processor, prices for CPU upgrade are falling quickly, which means a replacement processor for even a fairly recent Power Mac G4 makes a lot of sense.

Typical of the new breed of upgrade cards is Giga Designs' G-Celerator 1.4GHz G4 CPU upgrade. It will fit in any Power Mac G4 equipped with AGP graphics, which counts out the very first G4 Power Macs, but all others, up to and including the Quicksilver 2002, are supported by one of two G-Celerator options. We've tested the GC5A-1400-D2/A, which caters for any Power Mac with a 100MHz system bus. As well as a faster processor, the card has 2Mb of Level 3 cache and is fully Mac OS X 10.3-compatible. There's a matching card for 133MHz bus machines that does the same job for slightly more money.

Installation is simplicity itself. If you're happy upgrading RAM, you'll be quite at home swapping out your CPU. There's no driver software to worry about and the only fiddly operation involves installing a firmware upgrade prior to fitting the card. Not all of the compatible Macs will require

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this, but some will, as was the case with the Power Mac G4 450MHz used for our tests. A clear setup guide walks you through the installation, including the setting of five jumpers that determine the speed at which the CPU will run. By default it is set to 1.4GHz, but can be clocked (increased beyond its rated value) to a maximum of 1.5GHz to squeeze out that little extra.

Generally, clocking a CPU above its rated speed isn't a good idea, as the strains on the processor may lead to an early demise. But in our tests, the G-Celerator performed admirably at an increased 1.5GHz.

Suite as a nut

We used MacUser's standard suite of benchmarks to put the G-Celerator through its paces. These are designed to evaluate the gamut of a Mac's performance, from processor speed to disk drive throughput. Before and after results for the disk and screen redraw showed little variation, as these are functions of the disk drive and graphics card rather than the CPU. By contrast, our processor-intensive benchmarks showed a dramatic increase in performance.

The Photoshop test revealed a speed boost of almost 250%, while the FileMaker Pro test came in at just over 300%. Particularly telling was our Cinebench test, the best comparative test of overall processor performance, which showed an increase of 272% and was impressively close to the 1.6GHz Power Mac G5. Benchmarks aside, in everyday performance our test machine had a zip to it that was lacking prior to the upgrade.

At £399, the G-Celerator is a third of the cost of a new 1.6GHz Power Mac G5, which tips the scales at £1,190. It's not cheap, but for a quick fix to a lack of pace, the G-Celerator is seriously worth considering. Throw in as much RAM as you can, and a bigger hard disk, and you might still be getting by with the same Mac in three or four years time.