For years we've been using a variety of performance-based benchmark tests, like BAPCo's SYSmark, Futuremark's 3DMark, and our own venerable Winstones. Thus far, however, we've not had an energy-efficiency test that takes your daily life into account. The Energy Star 4.0 rating that the government certifies is based on "perfect systems" (without bloatware, applications, or extras) tested by the individual manufacturers, and those systems are tested only at idle and sleep states. We tested each system as shipped to the consumer with things like antivirus and Internet security software active if present.

Though it can be argued that most desktops and laptops spend most of their operating time in idle state (wherein they are running but most of their functions are not being used), there is still the matter of what happens when those systems are put under a load. We tried testing each one with BAPCo's SYSmark 2007 Preview to get a feel for what happens while running applications, but the measurements were inconsistent because SYSmark adds "realistic" pauses to the workloads. (BAPCo is currently working on an "EcoMark" test, but its release is a ways off.) Instead, we decided to use Maxon's CineBench R10 to get a consistent high-performance load over our test period. CineBench flogs the processor and memory (and keeps the screen on in laptops); it is a good measure of a scenario in which the computer is using the most power possible. With these criteria, we got numbers for off, idle, sleep state, and under load. We think this is a more accurate measurement of the real world than the simple idle and sleep ratings of Energy Star 4.0. We tested each system using a Kill A Watt meter, and used the results to come up with a graduated score for energy savings of 1 to 5.—Next: Desktop Energy Consumption >