Labs

£499 PCs

At the end of each review, there are five star ratings: one for Performance, another for Quietness, a third for Features & Design, then 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 array of benchmark results, objective scores and subjective quality ratings.

Performance

We put each machine through its paces in a rigorous series of tests using real-world applications such as Word, Access and Photoshop, using the same tests for PCs and notebooks.

The overall 2D result is relative to a score of 1.00 from our reference PC - a dual-core 3.2GHz Pentium D 840 system with 1GB of PC3200 RAM, a 10,000rpm Western Digital Raptor hard disk and an Nvidia GeForce 6600 GT graphics card. If a machine scores 1.50, it's 50% faster than our reference PC overall.

We test the 3D gaming capability of each PC using Crysis - the most punishing game in the world today. As well as pushing the latest cards to the limit of their abilities, it also tests their performance in DirectX 10. We run it at various levels, beginning at 1,024 x 768 with Low settings and rising to Medium settings at a resolution of 1,600 x 1,200, before shifting to the brutal 1,600 x 1,200 at the High settings. If a system gets a playable frame rate at this level we step up to Very High quality to push it further, before trying the monitor's native resolution as a final test.

Quietness

Unlike any other UK magazine, we send every PC in the Labs to a dedicated noise-testing facility to find out just how noisy it is. Testing is carried out in an acoustically treated listening room, using a precision sound-level meter with an "A-weighted" audio filter. The results are in dBA and, to put a rough perspective on measurements, levels of 25dBA can be compared to the background noise of a bedroom at night, while 45dBA represents background noise in a typical living room. Results are based on four readings: front and side while idle, and the same again but under intensive use. Intertek also measures the power consumption of each PC.

Features & Design

The Features & Design score takes into account an array of objective measurements, such as hard-disk capacities and setup, the capabilities of the optical drive and the inclusion of wireless, TV tuners and other extras. Warranties are examined and each company's performance in the Reliability & Service Awards 2007 is taken into account.

More subjective ratings are given to extras such as speaker sets and monitors, which can't be scored objectively. In these cases a panel of judges rate them on criteria such as style, build and sound/image quality, and the results are averaged.

Value for Money

The Value for Money score 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).

Overall

The Overall rating is a straight average of the Performance, Quietness, Features & Design and Value for Money scores. Occasionally it may appear higher or lower than expected due to rounding.