Power Cycle

Date: Sat, 11 Sep 1993 11:07:50 -0800 From: thorn@leland.stanford.edu (Shannon Thornburg) Subject: Macintosh Power Off/On Article Several people have requested copies of the article by Tim Oey on turning Macs on/off and how it affects computer lifetime. This is information that everyone who owns a Mac should look at, since it gives guidelines on how you can make your computer last as long as possible. Tim has generously agreed to make the information available electronically. Here is the latest version of that article, in text format. See the notes at the end for more information on distribution guidelines. (Moderators: this should probably be archived as something like info-mac/info/hdwr/power-cycle.txt or off-not-off.txt) ARTICLE BEGINS HERE To Off or Not to Off, That Is the Question by Timothy S. Oey Over the years, there has been much controversy about whether it is better to turn your computer off when it isn't used or leave it on continuously. This is not a simple question to answer, and as it turns out there are many different, but valid, answers. For the purposes of this discussion, we'll assume that "better" means that the computer will last longer. The simple answer to this question is: It's usually best to turn the computer off whenever it won't be used for 8 hours or more. So if you use your computer frequently during the day, as many do at work, turn it on in the morning and off at night. If you use your computer less (a home computer for example), then it is even more advantageous to turn your machine off. Besides, in both cases you'll save energy. Now if you'd like a more complete answer, or would like to know the details behind the above conclusion, please read on. The following information was distilled from numerous conversations with engineers at Apple Computer, Conner Peripherals, and Quantum Corporation. The conclusions reached are not necessarily those of any of these companies or the engineers, but they are an attempt to derive information which the average computer user should find helpful. To maximize the total number of successful operational hours for any computer device (i.e., maximize power-on hours), all computer devices (hard disks, CPUs, monitors, other electronics) should be turned on and left on forever until they fail. The number of power-on hours is what most engineers measure, and so they'll tell you to leave your computer on all the time to maximize them. But this does not necessarily mean that you, the user, will maximize the amount of productive time you get out of the computer. For instance, during the night the computer may be on but it may not be accomplishing anything for the user. Let's call this productive time the user's perceived system life span. It's the span of time over which the user is getting useful work out of the computer. Users are probably more interested in maximizing their computer's perceived system life span than the actual number of power-on hours. Regar…