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User Guide to Power Management in PCs and Monitors
4.1 Turn off computers at night and on weekends
One of the simplest and most effective ways to save energy is to turn off computers (PCs and monitors) when not needed, especially nights and on weekends. Sometimes computers are left on for legitimate reasons-for automatic backup or remote access, for example. However, many computers that could be shut off are left on by users who either mistakenly believe that shutting off their computer is harmful to the equipment or who simply forget to turn them off.
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 shut-downs. Shutting down computers at night and on weekends saves significant energy without affecting the performance, and may increase (rather than decrease) the operating lifetime of the equipment.
In cases where the computer is deliberately left on for network services or remote access, the monitor can be safely shut off without interfering with those activities. Since the monitor can consume two or three times as much electricity as the PC, turning off monitors is a big step in achieving significant energy savings.
Misinformation and bad energy habits are major stumbling blocks to achieving these energy savings. Computer users need to be informed about the real effects of shutting down their computers. Appendix B provides some resources for educating computer users about the benefits of shutting off their equipment at night and on weekends.