A: This is one of the more common questions I get. I believe one of the reasons I get asked this so often is due to the common advice that says you should leave your computer on all the time because turning it on and off shortens its life. Other people wonder the opposite: will leaving my computer on all the time burn it out?
Another reason I get this question so often is because people are concerned about their energy usage (especially now that power rates have gone up significantly in Illinois). The underlying question is how much power does my computer use and can I save significantly by leaving it off when I’m not using it?
I’ll first say that modern computers are designed so that they can be turned on and off without any negative effects. So don’t worry if you like to turn off your computer when not using it. You’re not hurting it, no matter what the common myth says.
The reason a common myth like this survives is because there may have been an element of truth to it at one time. While I can’t find any definitive proof, some older computers (like from the 70’s or 80’s) may have been fragile enough that repeated power cycling (a few times a day) could have worn them enough to cause damage to the computer (or more likely the power supply or power switch).
Secondly, most modern computers can run 24/7 for years and years without problem. In fact, the computer I’m writing this on has run nearly 24/7 for about 8 years now (let’s hear it for the Macintosh!). The life expectancy of most of the parts of a computer (except, notably, the hard drive – see my article about hard drive transplants) is far beyond the time the computer would become obsolete. So if you like to leave your computer on all the time, you’re not really hurting it either.
But if you do leave it on all the time, are you wasting electricity? That depends on what you define by wasting. According to the “Mr. Electricity” web site, a typical desktop computer uses about 65 – 250 watts of electricity when on. That seems like a lot, and it can be. However, most computers are set to go to sleep after a period of time. Mr. Electricity says a sleeping computer uses 1 – 6 watts. So if your computer is asleep most of the time, it’s using some electricity, but not a lot. You may still think that a few watts is worth saving. However, keep in mind that most computers still draw some power even when off. Usually this is around 1 watt. So you’d need to unplug your computer to make it totally stop drawing power. It really all boils down to a matter of convenience vs. saving power.
My recommendation is to make sure your computer is set to sleep and don’t worry too much about it. You’re not hurting it by leaving it on, and the small amount of power you’d be saving by turning off your computer or unplugging it isn’t probably worth it. If you are really concerned about saving power, there are many other things in your home that use more energy.