In addition to WorldBench 7, we conduct two other sets of tests on all PCs, running them through a series of game performance tests, and measuring their energy consumption. On laptops, we also measure battery life.
To test how well a PC runs modern games, we run benchmarks using Crysis 2 and Dirt 3. We run both games at two quality settings: The Low settings have reduced texture detail and effects, while the High settings turn the detail levels up. On desktops, we run both quality settings at four resolutions: 1024 by 768, 1680 by 1050, 1920 by 1080, and 2650 by 1600. In addition, we run an “Ultra” quality setting at 2650 by 1600 with all the settings--including all DirectX 11 features and antialiasing--cranked up. We measure performance in frames per second; higher scores are better, and a result of at least 30 frames per second is generally required for a game to be smooth enough for a good experience.
Laptops run the same two tests as desktops, but at resolutions more appropriate to the screens you find on laptops: 800 by 600, 1366 by 768, and 1920 by 1080.
We perform all tests that can run on a particular system (naturally, a laptop or all-in-one with a lower-resolution screen can’t run the highest-resolution tests). However, we don't use all tests equally in calculating a PC’s Performance score: On low-end systems, such as smaller all-in-ones and ultraportable laptops, we emphasize scores from the Low settings and lower resolutions. On performance desktops and desktop replacement laptops, we emphasize the High settings and higher resolutions.
WorldBench Green Score
The WorldBench Green Score is a measurement on a scale of 1 to 100 that evaluates a system’s energy usage relative to similar types of systems (laptops, desktops, or all-in-ones). For each PC, we measure the watts used and the time taken to complete the PCMark 7 productivity tests, arriving at the total watt-hours needed to handle that moderate workload. Then we let the machine sit for 15 minutes to measure how many watts the system consumes at idle, and convert that measure into watt-hours. We combine these results and compare them with results from similar machines. We weight 75 percent of the score toward the working watt-hours, and weight 25 percent toward the idle watt-hours.
We compare all standard desktops against one another, regardless of their category (performance, mainstream, or budget). All-in-one desktops, however, are an exception, as we compare them only against each other; since they have integrated monitors, we can't compare their energy use with that of standard desktop PCs. We compare all categories of laptops against each other. The higher the Green Score on the 1 to 100 scale, the less energy a system uses. We set laptop and all-in-one PC displays to a brightness of 95 cd/m2.
To measure laptop battery life, we first set the display to 65 cd/m2, or as close to that as possible. That’s a “low but readable” brightness setting, similar to what you would use when trying to save battery life. We then run a script that alternates between simulated typing at the command prompt and playing a full-screen high-definition movie (the same "Big Buck Bunny" video we use in our Video Encoding tests). The simulated typing runs for 10 minutes, then the full-screen video plays in VLC; we take care to ensure that hardware video acceleration is enabled in VLC. After 10 minutes of playing video, the script closes the video and returns to the typing test.
This loop repeats until the battery dies. We then fully recharge the laptop and repeat the test at least once to make sure that the results are consistent.