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Conserving Power

Environmental and money concerns make power management an issue for desktop as well as laptop users. Control Panel’s Power Options utility lets you configure hardware features that reduce power consumption, affect how the power switch works, and extend the life of computer parts by turning them off or switching them to a low-power state. The tabs and controls displayed in the Power Options Properties dialog box depend on the type of computer that you’re using (Figure 4.70).

Figure 4.70. Power Options detects what’s available on your PC and shows you only the options that you can control. A desktop computer has the top set of tabs; a laptop computer has the bottom set.


Tips

  • To use your computer’s power-management features, you may have to enable them in your system BIOS. When you boot your PC, you can configure the BIOS by pressing a key combination before Windows starts; consult the documentation that came with your computer or motherboard for details.

  • If your computer’s components don’t comply with the industrywide Advanced Configuration and Power Interface (ACPI) specification (also called OnNow), some power-management features may be unavailable or unpredictable. Older, non-ACPI-compliant computers have an APM tab (Advanced Power Management—an older standard) in the Power Options Properties dialog box.


Uninterruptible Power Supply

An Uninterruptible Power Supply (UPS) is a sealed backup battery—connected between the computer and the electrical outlet—that kicks in to keep your computer running if power fails. The UPS’s capacity is expressed in minutes available to save your work and shut down normally during a power outage—about 5 minutes for a cheap UPS and up to about 30 minutes for a higher-priced one. UPSes usually protect against power surges, spikes, and brownouts (low voltage), too.

A UPS doesn’t really have to interact with Windows, but Windows XP includes built-in support for monitoring that sounds power-failure alerts, displays remaining UPS-battery time, and—if power becomes dangerously low—shuts down the computer automatically. A UPS that plugs into a USB port will install its driver and make the Power Options UPS tab vanish, replacing it with Alarms and Power Meter tabs.


To optimize your computer’s power use, Windows uses a power scheme—a collection of settings that reduces the power consumption of certain system devices or of your entire system. You can use the power schemes provided with Windows or create your own, as you can a desktop theme.

To choose a power scheme:

1.
In Control Panel, choose Performance and Maintenance > Power Options > Power Schemes tab (Figure 4.71).

Figure 4.71. The timed power-savings settings depend on the power scheme you choose.


2.
In the Power Schemes section, choose a scheme from the drop-down list.

3.
To customize a power scheme, in the Settings section, change the default time settings.

4.
To create a new power scheme, select the time settings you want; click Save As; type a name; then click OK.

5.
To delete a power scheme, select it in the Power Schemes list; then click Delete.

6.
Click the Advanced tab (Figure 4.72).

Figure 4.72. The Always Show Icon on the Taskbar option is useful if you’re a laptop-computer user who changes between battery and electrical-outlet power occasionally.


7.
To put a power-plug (or battery) icon in the notification area, check the Always Show Icon on the Taskbar box.

Click this icon to choose a power scheme, or double-click it to open the Power Options utility.

8.
To password-protect your computer during standby or hibernation, check the Prompt for Password box.

9.
Click OK (or Apply).

Tips

  • On a laptop computer, the Power Schemes tab lets you choose independent settings for battery and plugged-in power.

  • Move the mouse or press a key to bring your computer out of standby mode. Press the power button to bring it out of hibernation. Your disks may take a minute to awaken from standby.

  • Turning off a monitor makes its screen go dark (and turns the green power light yellow). Turning off a hard disk makes it stop spinning.

  • Windows puts a computer into System Standby more rapidly than it does into System Hibernate. This makes sense, because you’ll want to put the system on standby if you’re away briefly and have it hibernate automatically if you’re away, say, overnight.

  • The details of Stand By and Hibernate modes are listed in Table 1.1 in Chapter 1.

  • Older systems may not support standby, hibernation, or software shutdown (powering off without the switch).


As described in “Logging on and Logging off Windows XP” in Chapter 1, you can choose Start > Turn Off Computer to stand by or hibernate manually, but it’s faster to use the computer’s power or sleep button.

To use the computer’s power button to stand by or hibernate:

1.
In Control Panel, choose Performance and Maintenance > Power Options > Hibernate tab (Figure 4.73)..

Figure 4.73. The Hibernate tab isn’t available if your computer doesn’t support this feature.


2.
Check the Enable Hibernation box.

3.
Click the Advanced tab (refer to Figure 4.72).

4.
In the Power Buttons section, select the action your computer takes when you press the Power or Sleep button.

5.
If you’re using a laptop computer, choose Standby from the drop-down list below When I Close the Lid of My Portable Computer.

6.
Click OK (or Apply).

For laptop computers, you can set alarms that sound or appear when the battery is almost out of power. Windows gives two distinct warnings: a low-battery alarm and the more urgent critical-battery alarm. When you hear either, you should save your work immediately. The alarm options let you specify which alarms you want (low-battery, critical-battery, or both); how you want to be notified (text, sound, or both); and what the laptop should do in response to the alarm.

To set a warning alarm for a low- or critical-battery condition:

1.
In Control Panel, choose Performance and Maintenance > Power Options > Alarms tab (Figure 4.74).

Figure 4.74. If your battery has a four-hour life, 3 percentage points is about seven minutes of use, but these settings are approximate.


2.
In the Low Battery Alarm and Critical Battery Alarm sections, check either or both boxes to set the alarms.

3.
Drag the sliders to change the power-level thresholds.

(Experience with the particular computer will help here.)

4.
Click Alarm Action to specify what happens when an alarm goes off (Figure 4.75).

Figure 4.75. At a critical power level, you put your computer in hibernation automatically (thus saving your work if you’re away from your laptop when the battery dies).


5.
Click OK (or Apply).

Tip

  • The Power Meter tab offers a graphical “fuel gauge” of remaining battery power, with a separate icon for each battery. Click an icon to get detailed information about that battery.


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