Power Consumption & Battery Life
Although power consumption is usually somewhat of an afterthought to most gamers with a high-end desktop PC, notebook owners are much more interested in how much juice their portable machine is using. A notebook that draws a ton of power will rapidly drain its battery, and throw off enough heat to make you wish you had a pair of asbestos undies. With that in mind, we plugged the Acer TravelMate 8100 with its 2GHz Pentium M 760 processor and Mobility Radeon X700 into our power meter to see what kind of power it was using in a couple of different circumstances...
Please keep in mind that this is TOTAL SYSTEM power consumption, and is not isolated to the Mobility Radeon X700. At idle, the machine drew a maximum of 38 watts of power. It actually hovered in the 26-30 watt range most of the time, but we've recorded the peak output here. To test how much power was being drawn under load, we fired up 3DMark05, and looped its built-in demo at a resolution of 1680x1050, with 4X anti-aliasing and 8X anisotropic filtering enabled. With 3DMark05 running, power consumption jumped by 36 watts, peaking at 74 watts. After about 20 minutes of the demo looping, the underside of the laptop got fairly warm, but never got to a point that we'd consider "hot".
To see what kind of effect taxing the GPU had on battery life, we also looped the 3DMark05 demo at 1680x1050 with 4X anti-aliasing and 8X anisotropic filtering enabled while running the system completely on battery power. After letting the battery charge completely, we started up the demo, and pulled the plug. It took a full 1 hour and 20 minutes for the notebook to die. And this was with the LCD at full brightness with PowerPlay disabled. Not too bad considering most of today's "desktop replacement" notebooks, powered by higher-end GPUs and processors, barely get 30-45 minutes from a full charge.