January 27, 2005

Turn On?

People often stop me in the street and say “Hey, Pete. Should I leave my computer on all the time, or turn it off when I’m not using it?”

Well, here are your answers. Once and for all. Real facts coming your way…

Q. Won’t leaving my computer on all the time consume lots of power?
A. Depends. If you left it working flat out on mathematical calculations, then yes – over £100 per year. If you leave it doing nothing with the monitor switched off, then about £15 per year. If you put it into “hibernate” mode, then it will consume sufficiently little power to be insignificant.

Q. Doesn’t turning it on and off wear out the components?
A. Yes, to an extent. However, you’d have to turn it on and off about a dozen times a day, every day to see any difference. The additional stress caused by turning it on and off twice per day isn’t significant enough to be worth considering as a factor.

Q. Does leaving it on all the time wear out the components?
A. Again, if you leave it on all the time when you aren’t using it, then you will shorten the life of the components, but really not by much at all. Very few home computers actually die because the components wear out – they are normally just abandoned because they become laden with spyware, junk or trojans, or they are replaced for a better model. Don’t let component life worry you.

Q. So give me a good argument against leaving it on all the time.
A. As long as you turn off the monitor to conserve power, the only argument I can think of is that while the computer is turned off, it can’t be attacked by miscreants. But then, as long as you’ve got a decent firewall, you shouldn’t really let that worry you.

Q. In conclusion?
A. Really, you can do what you like. As long as you aren’t bothered about £20 per year, there are no convincing arguments one way or the other. If you find yourself turning the computer on more than twice per day, then it may be worth leaving it on. Don’t leave the monitor on – that can waste a lot of electricity. If you want to save more energy, use hibernate mode.

Q. Where do the numbers come from?
A. A computer running at full pelt is about 200 watts, or 0.2 kilowatts. There are 8766 hours in the year. 0.2 * 8766 = 1753.2 kilowatt-hours. At 6p per kWh, we get £105.20 per year. When idling with the monitor switched off, the computer consumes about 30 watts, which is about 263 kWh in a year. This comes out at £15.78. These are only rough estimates, based upon an average computer and an average electricity tariff.

Q. Thank you. I shall not take these figures as gospel. I shall just use them to get a rough idea.
A. That’s the spirit.

UPDATE: As Lyle rightly points out in the comments, computers don’t like power cuts. Shame on me for omitting to mention this. If you live in an area with an unreliable power supply, then you should turn your computer off when you aren’t using it (though I expect that if you are in this situation then you have already bought a laptop). Also, if there is a storm brewing and you think that the power may go out, turn your computer off, switch it off at the wall, unplug it from the mains, and put the plug on a non-conductive surface (like plasticene or velvet).


16 thoughts on “Turn On?

  1. Dear Pete,
    I left my computer turned on as you said, under my stack of vitage playboys, to block out the noise. for some reason the playboys caught fire (and not because those ladies are hot) and my flat burned down.
    I blame you.

  2. Dear Pete,
    Should I leave my computer on when I’m giving it a thorough clean in a bathful of soapy water?
    Yours sincerely,
    Technofear P. Luddite (Mrs)

  3. Dear Pete,
    Should I try to leave my computer on when there’s a power-cut? Surely the sudden on-age when power returns has the potential to knacker a few components.
    Oh, and the sudden off-age has the potential to knacker the hard-drive.

  4. Adrian, magazines are not the right way to soundproof a computer. Most of the noise comes from fans in the computer. Instead of having a 60mm fan on your CPU and two 80mm fans in the case, get an 80mm fan for the CPU and a 120mm fan for your case. These give the same performance at a lower speed, hence quieter. Attach a rheostat to the 120mm fan, so you can run it at 800rpm when you are just surfing the web etc, and at 2400rpm when you are doing something that pushes the computer harder, like gaming. In this way you can keep the motherboard temperature below 30 degrees – utilities are available to monitor temperatures, for example mbprobe.

  5. I disagree Pete.
    Vintage playboys are NOT the right thing to use to soundproof a computer. Try Hustler instead.

  6. Oh baby, I love it when you get all technical (so long as it isn’t about RSS)

    Karen on January 28, 2005
  7. Ummmm… I’ll have to get back to you on that one, Vaughan.

  8. You said “miscreants” in normal conversation. That makes me happy.

    Nathan on January 28, 2005
  9. Can I get an RSS feed from my toaster, in order to let visitors to my website know when I’m having toast, and what kind of topping I’m spreading on it too?

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