If you plan to celebrate Earth Day by picking up a four-pack of compact fluorescent light bulbs, consider turning off your PC before heading out the door. Even when sitting idle, your PC or laptop consumes a considerable amount of electricity. An compact fluorescent light bulb is more energy efficient than an incandescent bulb, turning more of the energy it uses into light and losing less in wasted heat output. A 14-watt CFL bulb has the same light output as a 60-watt incandescent bulb, for example. Replace four 60W incandescents in your home with four 14W CFLs, and (assuming you keep those bulbs on for 8 hours a day and are paying 10.6 cents per kilowatt-hour) you stand to save $57 a year on your electric bill while reducing carbon dioxide emissions. Simply turning off your PC when it's not in use can save even more electricity.
CNET Labs tested the energy consumption of a mix of desktops and laptops recently and found that a mainstream desktop, on average, uses roughly 100 watts when idle. Under heavy use, that number jumps to 145 watts. You can double those figures for a high-end gaming rig with dual graphics cards and other high-powered components. Based again on paying 10.6 cent per kilowatt-hour, you'll spend $112 per year in electricity to run your gaming PC should you play games for 4 hours, leave it running idle for 8 hours, and keep it turned off for 12 hours. If you let it run idle around the clock for a year, you'll spend even more--$189 without once plugging in your game controller. (And you thought your bi-weekly expenditure at Game Stop was the only cost associated with your gaming habit.)
If you're replacing your light bulbs to create a greener home, you may also want to think about replacing your desktop with a laptop. Like a CFL bulb, a laptop requires a larger upfront cost, but can make it up over time with reduced energy costs. Using a broad mix of laptops, we found that the average laptop when plugged into a wall outlet uses 25 watts of electricity when idle and 62 watts when in use. If you leave your laptop plugged in all day and using the same scenario of 4 hours of heavy use, 8 hours running idle, and 12 hours powered down, you'll pay only $16 in electricity a year to power your laptop.
It's doubtful that gaming PCs will take on the aura of conspicuous consumption as, say, a Hummer, but leaving it running all day and all night certainly can be viewed as wasteful. A simple Earth Day tip for PC gamers would be to install an auto shutdown add-on or app that will shut down your PC at a specified time each day.
For more Earth Day 2008 posts, please see CNET News.com's Green Tech Blog.