Monthly PC Tips

Let Your Computer Sleep

March 2011 – by Per Christensson

While computers don't need sleep the same way we do, they still appreciate it. When you put your computer to sleep, it goes into an energy-saving mode that uses a minimal amount of energy. Therefore, whenever you step away from your computer for more than a few minutes, it is a good idea to put your computer to sleep. This may help extend the life of your computer and will definitely save you money on your energy bills.

So how much does sleep mode actually reduce energy consumption? Well, I ran a test on my Mac Pro to find out. My UPS (which I mentioned in my previous monthly tip) includes a small screen that displays the current wattage being used by the UPS. When the computer is running and both screens are on, the average power usage is 255 watts. When I put the computer to sleep, the wattage drops to 15 watts. Most of that wattage is probably coming from router and cable modem I have plugged into the UPS. Regardless, the power savings are significant:

255 W (running) - 15 W (sleep mode) = A savings of 240 watts

That is a big difference! If I left my computer running all day, it would be like leaving six 40 watt light bulbs on. I like to conserve energy when possible, so 240 watts is a big deal.

Fortunately, putting your computer to sleep is easy. If you have a laptop, just close it before you walk way. This automatically activates sleep mode on most laptops. (Closing your laptop has the added benefit of protecting your screen and keyboard from external dangers, such as a curious cat or roaming children.) If you have a desktop computer, you can put it to sleep with a simple command. In Windows, simply select Start Menu → Standby to activate sleep mode. In Mac OS X, you can put your computer to sleep by selecting Apple Menu → Sleep. The keyboard shortcut Command+Option+Eject also works.

Putting your computer to sleep when you're not using it is a simple step that can save a lot of energy. Therefore, it's a good habit to get used to.

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