Optimizing your computer's power usage

Not so long ago our computers were either "On" or "Off." These days Windows gives us a huge number of potentially confusing power options, from "Stand By" to "Hibernate." This article will help you understand the jargon and configure your PC's power management, which could help you save a few bucks on your electric bill.
Published: Aug 16, 2007
Author: Jordan Running
Related OS: XP / Vista

Back in the old days, whether your computer was on or off depended solely on the position of one big switch on the front. Nowadays we have a lot more options when it comes to our computers' power states, some of which can help lower your electricity bill. Even so, many people still have a "one big switch" mentality, usually only using the Shut Down command and never digging deeper into their PCs' robust power management options. There are better ways, however, and I'm here to tell you about them.

There's some potentially confusing jargon we should get out of the way before we begin. Here's some terms you'll encounter in Windows:

Turn Off/Shut Down: Turn Off and Shut Down are two terms for the same action in Windows: When you select Turn Off or Shut Down, it quits all of the programs that are running, saves your settings, stops the operating system, and turns off the computer competely.

Restart: When you Restart your computer, it is completely Shut Down as above and then immediately turned back on automatically.

Stand By: When you put Windows XP in Stand By mode, your session (i.e. all of your open programs, everything that's on the screen, even the position of the mouse) is saved to RAM, and every other component of your system is turned off. A small amount of power is still used by RAM (Understanding Computer Memory), because if RAM loses power all information stored in it is lost. When you turn your computer back on, the session is loaded from RAM, allowing you to pick up where you left off very quickly.

Hibernate: Hibernate is just like Stand By, but instead of saving your session in RAM it stores it on your hard drive, then turns off the computer completely. Unlike Stand By, your computer will not draw power in Hibernate mode, because data stays on the hard drive indefinitely, even when there is no power. However, since it takes longer to read data from the hard drive than RAM, it takes longer to boot from Hibernate than from Stand By, but less time than from a complete Shut Down.

Sleep: Sleep is a new mode in Windows Vista that replaces Stand By. It puts your computer in the equivalent Stand By mode, but also saves your session to the hard drive. This way, you can resume your session quickly, but if you lose power your session is not lost. Also, it can be configured to automatically power down after a certain amount of time (but can still be resume as from Hibernate).

That's a lot of options for machines that not so long ago had just "On" and "Off." Now we're going to see to set up Windows to enter power-saving modes automatically.

Windows XP

To configure power management in Windows XP, go to the Control Panel and open Power Options. It will open to the Power Schemes tab. "Schemes" are different sets of options pre-configured for different kinds of computers, and the quickest way to get started is to choose the appropriate scheme for your computer from the drop-down menu.

Windows XP Power Schemes

They're pretty self-explanatory, so I won't go over them all. The "Presentation" scheme is a special case, however, and very useful: If you're giving a presentation, you can choose Presentation and it will ensure that your computer doesn't unexpectedly go into, say, standby mode, which could be inconvenient and embarrassing. "Always On" keeps all of your computer's components on all the time, except for your monitor, and "Minimal Power Management" just turns off most of the options. "Max Battery," of course, tries to turn off components whenever possible to conserve battery power.

After choosing a scheme you can customize it, if you want, using the options below. My definitions above should make most of them clear. In each case, you can choose the number of minutes or hours with no keyboard or mouse input (i.e. when you're not using the computer) before the computer will take various power-saving measures. The most potentially confusing option is "Turn off hard disks." It works like this: Even when you're not accessing the data on your hard drive, your computer keeps them spinning so that it can quickly access any data you might suddenly need. It takes a significant amount of power to keep them spinning. The "Turn off hard disks" option will instead turn them off after a period of inactivity. The only downside to this is that it takes some time--a few seconds--to "spin up" the disks again after they've been stopped, so you'll experience a momentary lag if you try to open a document or run a program after such a period.

If you've made any customizations to the power scheme, you can click Save As... to give it a new name. If you just want to change the existing scheme, or if you haven't made any changes, you can click on OK or Apply and your chosen scheme will kick in immediately.

On the Advanced tab you'll find a few more options, which aren't really very "advanced." In fact, they're pretty self-explanatory. You can choose what happens when you press the power button (i.e. which of the power states above your computer will enter), and whether you'll need to enter a password when you resume from standby or hibernation. "Always show icon on the taskbar" refers to the battery/plug icon that appears in the notification area (next to the clock). This is convenient if you have a laptop, but not very useful if you have a desktop that never runs on battery power.

The Hibernation tab lets you enable or disable the hibernation option. There's no real reason to have it disabled, but this tab will tell you how much disk space you'll need to set aside, since to hibernate the computer must write the entire contents of your RAM to the hard drive. Lastly, the UPS tab is for use with an Uninterruptible Power Supply, and beyond the scope of this article.

Windows Vista

Windows Vista has mostly the same power management options as Windows XP; they're just arranged much differently. You can find them the same way, however: Go to the Control Panel and open Power Options. The main screen lets you choose among several "power plans," which are analogous to XP's power schemes. One nice thing is that Vista tells you what trade-offs you're making between battery life (if you're on a laptop) and performance.

Vista Power Options

You can choose one of these and be done with it, or you can click on the "Change plan settings" link to customize the plan just like in XP. Microsoft has changed around a few terms, however: "monitor" is now "display," "standby" is now "sleep," and so on. If you have a laptop, it also gives you separate settings for when you're plugged in and when you're running on battery power, and you can choose to dim the display in order to conserve battery power.

Vista Power Options Plan Settings

Clicking on "Change advanced power settings" on this screen will let you make even more granular changes to your options. Feel free to poke around--you can't really break anything here--but I won't go into this area in depth, except to say that if you find your wireless adapter turning off for no apparent reason, try choosing "Maximum Performance" under Wireless Adapter Settings > Power Saving Mode.

Back on the main Power Options screen, the left sidebar has links to other options, most of which we saw in Windows XP. The first three all take you to the System Settings page, which lets you choose what the power buttons do, what happens when you close your laptop, and whether you'll be prompted for a password when you resume from sleep or hibernation.

Vista Power Options System Settings


You could spend hours tweaking your power management options in Windows, but the truth is there's no "perfect" configuration. The settings you should choose depend entirely upon your usage habits. I recommend picking a few settings that look "good enough" and sticking with them for a few weeks. If you find it isn't optimal for you, you can go back in at any time and change it. Hopefully, however, this article has given you a good start and maybe saved you a few pennies on your electric bill.

About Jordan Running

Blogger since 1999, Jordan Running went pro in 2005 and never looked back. Sometimes programmer, occasional photographer, and serial tinkerer, he decided to to switch to Linux in 2001 but just hasn't quite gotten around to it yet.

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