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As energy costs rise, PC power conservation can trim $100 or more from your total electric bill each year. That's enough for a nice dinner with your spouse--or if you're not the romantic type, it can get you a few months closer to purchasing a new, faster (and more energy-efficient) system.

Depending on their age and design, a desktop computer and monitor consume from under 150 watts to greater than 800 watts when in use, and from fewer than 50 watts to more than 400 watts while turned on but idle. For this article I used a watt meter to measure the power consumed at the outlet by a 3.4-GHz Pentium 4 system with 1GB of RAM, an 8X AGP video card, two internal hard drives, an optical drive, and a 19-inch LCD monitor. This is not a high-end machine by any means; I selected it because it demonstrates how a few simple tricks can help reduce the amount of electricity an average system uses by more than 50 percent. This relatively modest PC varied from a minimum of 195 watts while idling at the Windows desktop, with no applications running, to 305 watts with the processor and graphics under 100 percent load; its average power rate was 250 watts.

Such figures may not seem substantial when you consider that dual- and quad-core processors consume 130 watts or more each at full load (however, new CPUs manage power more efficiently when they're not running under full load, so they may consume less power than older, slower processors). Also, high-end graphics cards use nearly 200 watts each. Still, if you were to allow this system to operate continuously, it would easily run up more than $200 in energy costs over the course of a year. Fortunately, you can apply changes to several configuration settings to bring the power consumption and operating costs of any system down significantly.