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Frequently Asked Questions (FAQs)

1. Why should I use power management features?

Easy money. You can save up to $50 or more per computer by activating system standby or hibernate features.

2. I have my screen saver activated. Do I need to activate power management features?

Screen savers generally do not save energy. In fact, certain graphics-intensive screen savers can cause the computer to burn twice as much energy, and may actually prevent a computer from entering sleep mode.

Screen savers were originally developed to prevent the permanent etching of patterns on older monochrome monitors. Modern display screens do not suffer as much from this problem, but screen savers are still used for entertainment.

If you want to use your screen saver in conjunction with monitor power management, set the screen saver "wait time" to less than the period of time after which the monitor enters sleep mode. If your screen saver appears but your monitor never enters sleep mode, your screen saver may be the culprit: try disabling it.

3. Do computers and monitors use more energy with power management features activated due to power surges when cycling on and off?

A popular myth holds that leaving lights, computers, and other appliances on uses less energy than turning them off and also makes them last longer. In reality, the small surge of power created when some devices are turned on is vastly smaller than the energy used by running the device when it is not needed.

Source: "Eleven Energy Myths: From Efficient Halogen Lights to Cleaning Refrigerator Coils", Lawrence Berkeley National Labs

4. Can sleep features wear out hardware by forcing the computer to turn on and off several times a day?

“Modern computers are designed to handle 40,000 on-off cycles before failure, and you’re not likely to approach that number during the average computer’s five- to seven-year life span. In fact, IBM and Hewlett Packard encourage their own employees to turn off idle computers, and some studies indicate it would require on-off cycling every five minutes to harm a hard drive.”

Source: Rocky Mountain Institute Home Energy Brief #7 Computers and Peripherals.

“The belief that frequent shutdowns are harmful persists from the days when hard disks did not automatically park their heads when shut off; frequent on-off cycling could damage such hard disks. Conventional wisdom, however, has not kept pace with the rapid technological change in the computer industry. Modern hard disks are not significantly affected by frequent shutdowns.”

Source: “User Guide to Power Management for PCs and Monitors”, Bruce Nordman, Lawrence Berkeley National Laboratory, January, 1997, LBNL-39466

5. How can I tell if my computers or monitor is enabled for system standby or hibernate?

Windows users can check power management status via the control panel: for assistance, see our detailed and illustrated manual instructions.

If your monitor screen goes dark and appears to be off after a period of inactivity, monitor power management is enabled. If, in addition to the monitor darkening, the low hum of your hard drive stops after a period of inactivity, either system standby or hibernate is probably enabled.

6. Can system standby and hibernate features render a computer unstable, causing system crashes and/or preventing it from waking?

While problematic in early versions of Windows, today’s sleep features almost never cause system crashes or keep computers from waking. Machines running Windows 2000, XP, Vista, and Mac operating systems should not experience these problems.

7. Do power management features save energy on notebook computers, too?

While they use less energy than desktops, notebook computers still burn about 20–30 watts of power. System standby and hibernate features reduce notebook power draw to 1–2 watts, so the energy savings are still very significant. Be sure to activate system standby and hibernate features in the AC power profile (which saves power when the notebook is plugged into the wall) — not just the DC power profile (which prolongs battery life.)

8. What’s the difference between “system standby,” “hibernate,” “monitor power management,” and “turn off hard disks”?

There are 4 basic types of computer power management, or “sleep” features on Windows PCs:

  • “System standby”
    • Drops monitor and computer power use down to 1–3 watts each
    • Wakes up in seconds
    • Saves $25–75 per PC annually
  • “System hibernates”
    • Drops monitor and computer power use down to 1–3 watts each
    • Wakes up in 20+ seconds
    • Saves work in the event of power loss
    • Saves $25–75 per PC annually
  • “Turn off monitor”
    • Drops monitor power use down to 1–3 W
    • Wakes in seconds or less
    • Saves half as much as system standby or hibernate: about $10–40
  • “Turn off hard disks”
    • Saves very little energy

9. I understand that Microsoft ships Vista with computer power management settings enabled. So there is no need to activate sleep settings on Vista machines, right?

While Microsoft does ship Vista with sleep settings enabled, operating systems are usually installed by PC makers, IT departments, computer resellers, or 3rd party service providers. Windows Vista default power management settings are not typically retained.

Even if the Vista default settings are retained, you may prefer to modify the settings in order to save more energy. To maximize power savings, EPA recommends setting computers to enter system standby or hibernate after 30 to 60 minutes of inactivity. To save even more, set monitors to enter sleep mode after 5 to 20 minutes of inactivity. The lower the setting, the more energy you save.

10. Because I access my desktop computer remotely (e.g., through VPN), I leave it powered 24/7. Can I still use power management features?

11. If my computer is in system standby or hibernate mode, how will it receive important software updates such as new antivirus definitions and Windows security patches?

For individuals and organizations without centralized IT departments, computer software is generally pre-configured to automatically download and apply updates shortly after resuming from system standby or hibernate.

In enterprises, there are numerous ways for network administrators to ensure that software updates are applied:

  1. Configure client computers to apply software patches and updates as soon as the computer becomes available on the network.
  2. Windows Task Scheduler can wake up sleeping computers for updates. Scripts distributed via Active Directory can allow one to centrally manage these “scheduled tasks.”
  3. With Wake-on-LAN activated, a network administrator can wake up sleeping machines at any time in order to perform on-demand software patches or updates.

12. The configuration is correct and all the settings are showing up in the control panel on the machines, why are the computers not going into standby?

There are three main reasons that your computer could be behaving in this manner:

  1. In some instances, old drivers or generic drivers are not compatible with sleep settings and will not allow the computer to sleep. All drivers should be updated and generic drivers should be removed.
  2. In some instances, there may be a subset of computers that are not consistently sleeping. In those cases, evaluate if a unique piece of software is on these machines exists. If so, that software may be the cause. Contact the software maker and see if there are updates available that are compatible with sleep settings.
  3. In some instances, computers may appear to be randomly not sleeping. In these cases, look for:
    1. a file open on the network;
    2. something causing too much activity on the CPU (complex screen savers, software running in the background, etc.)

13. What does it cost to implement computer power management on a large network of computers?

There are two categories of costs to consider: 1) labor costs, and 2) software costs

  • Labor costs include time spent (usually by IT specialists) identifying appropriate solutions for your unique computing environment, testing solutions and troubleshooting exceptions, and ensuring that sleeping computers do not interfere with administrative software updates. For most organizations, labor costs rarely exceed about $5 per computer in total. This number is based on our experience assisting dozens of organizations that ranged in size from a hundred to tens of thousands of computers.
  • Software costs range from zero to about $15 per computer. Many solutions utilize public domain software tools, and/or tools that you may already have at your disposal. Commercial software packages typically offer more feature-rich solutions and may deliver more energy savings, but they involve fees of roughly $3-15 per PC.