Labs

Media Center PCs

At the bottom of each review, there are five star ratings: one for Performance, another for Quietness, a third for Features & Design, one for Value for Money and a final Overall rating. We don't just pluck these figures out of the air: they're calculated using a complex mixture of benchmark results, objective scores and subjective quality ratings.

Performance

The Performance rating is based on each machine's scores in our 2D and 3D benchmarks. This month, we give them a weighting of 75 per cent and 25 per cent respectively, since gaming performance isn't a high priority with Media Center PCs. And, as you'll see from the overall 2D performance graph, there's very little to distinguish the best from the worst this month.

Each score in the 2D performance graph is relative to a 3.2GHz Pentium D 840 desktop PC with 1GB of PC2-4300 RAM. If a machine scores 0.75, that means it's 25 per cent slower than the reference PC overall. The figure is derived from the system's performance in a number of real-world applications, including Microsoft Word, Excel and Access, as well as CorelDRAW and Photoshop. We also run media creation benchmarks, including converting an AVI file to MPEG2 and DivX, and converting a WAV file to the WMA, MP3 and OGG Vorbis formats.

We use Far Cry to test each system's 3D performance. Tests are run at 1,280 x 1,024 with detail levels set to Very High, and anti-aliasing and anistropic filtering are set to 4x and 8x respectively.

Quietness

To accurately measure each system's noise levels, we take them to Intertek Research & Testing centre in Milton Keynes, where testing is carried out in an acoustically treated listening room, but under typical user conditions. A precision sound-level meter with an 'A-weighted' audio filter is used to help relate the pressure measurement to subjective impression. To put a rough perspective on the measurements, levels of around 25dBA can be compared to the background noise of a bedroom at night, while 45dBA represents typical living-room background noise.

Quietness is vital this month, as everyone expects a hi-fi component to operate silently. This is why measurements are taken when idle from the front and side, and again from the same positions with a DVD playing. The graphs above summarise the most important results. Full results, including power consumption, are detailed in the technical reports, which can be found on the cover disc.

Features & Design

The Features & Design score is calculated using a huge array of scores that we give to each machine, based on objective measurements like the range of audio and video connections, as well as the degree of customisation offered by manufacturers. We also give scores to any bundled software and the type of warranty given.

The Features & Design rating includes some subjective scores, which are decided by a panel of judges; this helps to overcome any bias resulting from one person's taste. The subjective scores cover all those items that can't be measured objectively, such as the quality of the build and design of the chassis.

Value for Money

Our Value for Money rating is based on a weighted average of the Performance, Quietness and Features & Design scores; we then factor in exactly how much each machine costs (including delivery) to give a bang-per-buck result.

Overall

The Overall rating is a straight average of the Performance, Quietness, Features & Design and Value for Money scores.