More energy efficient to leave laptops/desktops on?

SideWinder

SideWinder

SideWinder

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Having a heated argument with a flatmate who claims her Dad knows more than anyone in the entire world about anything related to computers...

I have always believed that it is best to leave laptops/desktops on as it uses less power than always powering them up and down whereas she believes that is stupid and everything should be switched off.

So i need a few websites or whatever to either prove myself wrong (:o) or shut her up.

Laptops and desktops...quite different when it comes to power, obviously?
 
most take less than a few minutes at the most to boot in to windows, not fully loading the pc while its doing so. so unless your switching it on and off every 5 minutes then no, leaving them on isnt more efficiant at all.
 
james.miller said:
most take less than a few minutes at the most to boot in to windows, not fully loading the pc while its doing so. so unless your switching it on and off every 5 minutes then no, leaving them on isnt more efficiant at all.
Click to expand...

Same for laptops? Interesting. I've always believed that you need 100% power to turn on the laptop/desktop and then it starts to go down the % until it idles or so, thus using less power...
 
the power surge is fairly minimal when turning on a computer and only lasts a few seconds, even if you had say a 50% higher surge power to idle you would cancel it out after a few seconds of having the machine off
 
well even if it it did fully load the pc or laptop, it'd only do so for about 2 minutes. using my laptop as an example, your talking about two minutes at full load (60w or so) and switching it off for maybe....3 hours and leaving it idling using 30w or so for 3 hours.
 
I dont see how leaving your average desktop of around 125w idle on is more energy efficient than turning it off when your not using it. Especially if it has a peak load of even around 250W (and that'd be with a pretty good graphics card).

I do leave my PC on all the time though, its my main PC but it also serves as a download machine/file storage.
 
Makes no sense to me. Leave something on using power all the time or turn it off and use no power. The smallest of surge to turn back on is no where near the power you'll save by turning it off say all night.
 
So it doesn't make a difference...basically? Because the time for surge versus the time for leaving on makes up for it? /confused. :o
 
Yes. Just say the system used 250W for a few mins when you turned it on, and then 125W idle after, the 50% extra watts for a few mins is neglegable.
 
I don't really understand the whole 'powering up' bussiness, I mean your putting a bit of extra of a load booting up, nothing much more really, people make sound like a space shuttle launch when it's not.

It's believed not to be good for a hard drive to be powered on/off all the time, I would recommend making sure Windows XP is set to NOT switch them off after xx minutes.

If it's <20 minutes then, you are probably better leaving it on as you'll have to start Windows all over. Unless you have a reason then it's probably better to power down the computer when your going to work or bed. Or use hibernate?

Most computers probably pull about 80-140W when idle. Let's say it's 100W, then 10 hours is a kW, which amounts to 8 pence or something, overtime I supose it saves money.

Bottomline: I'd recommend when going to work or bed to power down unless you run servers, torrents or have a reason.

In fact I have a watt-measure thingy, it tells me my computer uses 115W idle, powering up it's about 130W (not 100%), I've never seen it go 180W+ although I need to re-test it to be sure.
 
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With the small difference between boot and idle of most new computers the only way you would benefit from leaving them on all the time is if you were turning them off and then within a minute turning them on again.

As an extreme example say at idle your PC uses 200W but on boot up it uses 400W a 100% difference.

You argue to leave it idle for one hour and then use it again so your power usage would be 0.2KWh.

Your flat mate would like to turn it off for the hour and then turn it on when needed so lets say 1min to boot to make it simple. So it uses 400W for 1min in the hour which works out at 0.4KW/60 which gives 0.007KWh.

For your assumption to be valid and the above example to work out cheaper to leave the PC on it would have to have a start-up surge of around 12KW or 60x it's idle usage :eek: (think my maths is OK but I've had a long day).

The main reason for leaving computers on is reducing thermal cycling and stability, you don't leave them on because it's cheaper than turning them off :D
 
I always turn mine off. If it goes pop all my stuff is under warranty, so i'm not fussed. Plus, my gaming rig uses a fair amount of power, even on idle, so i'm saving money hopefully! Actually looking at those asus eebox machines as an alternative for work.

You could confirm this by using one of those watt-meter thingys and test it over a few hours.
 
I thought it was only an advantage for massive companies to leave machinery on. They say it would take way too much time and power to get it going again, so it would make more sense to leave it on.

BTW, I just use 'sleep' under Vista whenever I don't need my laptop.
 
just put your desktop into sleep and turn off monitors if you are going to be away from it for 30 mins or so. longer than this then shut down.

laptops just shut the lid. i never turn off my laptop - waste of my time waiting for it to boot!
 
I think this confusion is coming from not understanding the difference between Power and Energy, and people interchanging these words readily - they are not the same. Power efficiency is also not equal to energy efficiency.

Power means how much energy is used per second(watts), and is not a measure of energy(joules).

If you have a laptop pulling 100w on startup and it takes 1 minute to start this means it uses 100x60=6'000 Joules of energy to start, if it then idles at 50w power use it will use a further 50x60=3'000 Joules of energy every minute. So in this example two minutes of idling uses the same energy as starting the laptop, idling for longer then two minutes means you are using more energy then required to startup.

So the answer is no, the only thing it saves is time.
 
I very rarely actually shut down my PC or notebook. My PC goes on Sleep if I'm going out or before I go to bed, and I use Hibernate on my notebook to make start-up faster.

Only time I'll shut down is if updates have been installed while I've been using it, in which case I'll shut it down when I'm finished so they can be installed properly.
 
The big issue about turning any electronic device on and off when not in use is breaking it. Things generally only tend to go faulty when you turn them on or off - not during use.

You will save money on power by turning your appliances off when you are not using them. You will, over your life time, have to spend a little more on replacements and repairs.

Having said that with screens it is probably always worth dropping them into standby whenever you walk away from you computer.

I used to leave my computers on 24x7 but now I turn them off every night before bed, or if I know I wont use them for many hours. I reckon this is saving me a fair bit of money. I don't use power saving features or hibernate features.
 
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