October 2003
Volume 7, Issue 1

Inside this Issue...

Social Science Computing Laboratory

Faculty of Social Science
Room 1228, Social Science Centre
The University of Western Ontario
London, Ontario, Canada, N6A 5C2

E-mail: ssts@uwo.ca
Web: www.ssc.uwo.ca/ssnds
Phone: 519 661-2152

Managing Editor: Ramona Fudge
Layout: Mary Van de Ven

PC Power Consumption Tips

Les Flodrowski

Even prior to the August 14th power failure and heightened concerns for energy conservation, computer users often asked if it was better to leave their PC on all the time or power it off. In response to this question, SSCL has performed some tests and done some research that we would like to present in this article.

Our tests show that, although there is a slight surge in power consumption whenever a device is first powered on, a typical PC consumes close to 60 watts of power in its idle state. As well, a standard 17” CRT monitor consumes another 58 watts, and a 17” LCD display consumes about 48 watts. Therefore, the total power consumed by having both your PC and monitor on roughly equals the power consumed by two 60 watt light bulbs.

It should be noted that modern computers and monitors are built with energy saving features that you can enable to reduce power consumption. The following sections provide some tips and suggestions to help you reduce energy usage in your office and at home.

Turn Things off Whenever Possible
Most people turn off the lights when not in use. It stands to reason that computers and peripherals such as printers and scanners should also be turned off when not in use, at night and on weekends. After all, turning off your PC and monitor is equivalent to turning off two 60 watt lights!

Screen Savers
Contrary to popular belief, screen savers are not energy savers. A screen saver often displays a moving image and will cause your monitor to consume as much energy as it does when in use. In fact, using a screen saver involves CPU interaction which results in additional power consumption. The best way to save energy is simply power off your monitor when not in use, even if you leave your PC on. This will also help extend the life of the monitor and eliminate the possibility of electromagnetic radiation emanating from the monitor. The next best way to save energy is to take advantage of your computer’s power management features.

Enable Power Management Features
Thanks to the U.S. Environment Protection Agency (EPA), today’s computers and monitors are easily programmed to automatically reduce their energy use by 60 to 70 percent when left idle. The following simple steps outline how to enable your computer and monitor power management features for Windows XP:

• Click Start > Settings > Control Panel.
• Open Display and click on the Screen Saver tab.
• Click on the Power… button.
• From the Power Schemes drop down menu, select the Home/Office Desk Power scheme.
• In the Settings section, select the desired settings for your monitor, hard disk and system. Typical settings are:
    1. Turn off monitor: After 20 mins.
    2. Turn off hard disks: After 30mins.
    3. System standby: After 1 hr.

By having your monitor turn off automatically, you will start saving energy whenever your computer is idle such as during lunch breaks and meetings.

Enable Security
It is a good idea to password protect your computer so that no one else can enter your Windows session after you’ve been away from your computer for a short while. This is accomplished by enabling a blank screen saver as follows:

• Bring up the Screen Saver tab as described above.
• From the Screen saver list, select Blank and enable the option: On resume, password protect.
• Select the desired Wait time. Usually this time is equal to or less than the time after which your monitor turns off (e.g. 20 minutes or less).

It’s Okay to Turn Your Computers Off
A common belief is that a computer’s life is shortened by turning it on and off, resulting in many people leaving their computers on at all times. Most experts, however, agree that turning computer equipment off at night and on again the next business day does not appreciably affect its life. In fact, hours of operation and heat are the greatest factors that reduce the life of equipment. Both these factors are reduced when you switch your computer, monitor and peripherals off when not in use.