Labs

The Power Mac G5 line is the power user's favourite: a Mac with lots of muscle, ample room for expansion, and the arresting tough-guy aluminium case design. It's also the line with the biggest variance between the bottom and top ends of the range. It starts with the single-processor 1.8GHz G5, a model with as much in common with its iMac cousins as with the rest of the Power Mac line, and goes right up to the dual-processor 2.7GHz G5. That's a 50% speed jump even before you factor in the second processor. If it wasn't for the fact that the single-brained 1.8GHz model slips in at less than £999, we'd have expected this model to have been dropped by now.

Every graphics card that ships with the Power Mac G5 range includes dual-display support, which means they can drive two monitors directly without the need for a second card. However, the card fitted as standard in the slowest Power Mac G5 has 64MB of RAM, which means each of the two connected displays would effectively only have 32MB available. If you plan to use two screens extensively, especially if one or both is reasonably large, then trade up to a card with at least 128MB of memory instead.

The dual-processor 2GHz model isn't quite the same as the older 2GHz model it replaces. The new model shares the

The divide between the better Power Macs and the not-so-great ones is made clear with the optical drive, too. Here, the 1.8GHz Mac's 8x SuperDrive is significantly less impressive than the 16x dual-layer drives in the other models, and certainly points to this model being dropped off the product list sooner rather than later. The dual-layer support of the faster drives means up to 8.5GB can be written to a single dual-layered disc.

The Power Mac G5 design includes a greater number of fans than in any previous Mac model. Fortunately, these are managed intelligently by the Mac OS and only run at 10% of their full 5000rpm. As a result, these Macs still run much more quietly than late-model Power Mac G4s. As well as the half-dozen or so fans, the top-end 2.7GHz Power Mac also has a liquid cooling-system to keep the processor heat under control.

The single-processor model aside, the Power Mac G5s do run impressively fast, although you'll only see the true benefits with applications such as Photoshop if you upgrade your RAM well beyond the standard 512MB.

If you want a really fast Mac, there's no question about whether or not you should consider a Power Mac G5: there's no realistic alternative when it comes to unbridled power. Which model you choose is less clear. We advise writing off the single-processor 1.8GHz model from the start, and the RAM limits of the new 2GHz Power Mac puts a question mark over it as well. It's then a choice between the 2.3GHz and the 2.7GHz models, and the only person that can make that decision is you. Or your bank manager.