What's the most energy-efficient power management option for my computer?
November 20, 2004 6:00 PM   Subscribe

Give Me X An IT guy at work told me I shouldn't be shutting down my computer every night because starting up the computer every morning wastes more power than I've saved. I find this hard to believe, but of course I want to use the most energy-efficient option, both at home and at work. So, assuming I've set up screensaver and standby options on my computer, what's the rule of thumb for shutting down? In the equation "X or more hours of non-use = better to shut down and start up later", what does X equal?
posted by orange swan to Technology (23 answers total)
Here's an old AskMe, somewhat related. And ZDNet article about this.

The Department of Energy addresses this, too - concluding that "If you are not going to be using your PC for more than around two hours, turn the CPU and monitor off." But they also note that the time you wait to shut down/boot up is worth a lot more than the electricity you are saving.
posted by milkrate at 6:29 PM on November 20, 2004

They should also note that temperature fluctuations contribute to early component failure. The energy required to manufacture a new computer is surely more than the energy it would take to run it 24/7 for the rest of its natural life.
posted by five fresh fish at 6:39 PM on November 20, 2004

five fresh fish this used to be the case back maybe 10 years ago or so when quality control for PC parts is not what it is today (assuming you're buying from good manufacturers like Asus, Corsair, etc.) - my understanding is that these days it really doesn't much matter which way you go.

On the other hand, leaving it running does eat it up more power. Personally, the convenience of instant-on is worth it to me to never shut down, and it helps that my security situation is pretty tight.
posted by Ryvar at 7:29 PM on November 20, 2004

WAS not what it is today, sorry.
posted by Ryvar at 7:29 PM on November 20, 2004

For modern power supplies, X = 0. Or close enough.
posted by majick at 8:15 PM on November 20, 2004

Starting up a computer uses no more energy than normal operation. The thermal stress on components is minimal, and has no effect on failure rates. So follow majick's formula...when it's on, it's using power. When it's off, it's not.
It's that simple.
posted by rocket88 at 9:06 PM on November 20, 2004

If your computer supports suspend - use that. You get the convenience of instant on and you save almost all the power that you would by turning it off. I've been doing the turn off/suspend thing for 15 years and I haven't had any better or worse luck with hardware failure than the people that just leave their computers on. I have saved money on electricity, though.

I think the "using more power starting up" misnomer carries over from the perhaps-true aphorism of turning a car off and starting it up uses more gas than just letting it idle for X number of minutes.
posted by zsazsa at 9:14 PM on November 20, 2004


Most systems do actually use more power at startup than say, idle- they spin up their hard disks, go through POST tests, and x86 machines are executing the BIOS at full throttle. The power surge is minimal, though, depending on how many devices your system has. It's no more than 5-10 minutes of juice during idle.

I personally run my machines 24x7. I do it out of convenience, so I can remote access my network and it's resources at any time.

As long as your not toggling the power on a machine like it's an arcade-fighter, it really doesn't matter what you do.

Suspend mode is a nice trade-off, though.
posted by id at 9:53 PM on November 20, 2004

five fresh fish this used to be the case back maybe 10 years ago or so when quality control for PC parts is not what it is today

Ryvar... Quality control isn't an issue of time or manufacturer! :-D

In fact, I think we're back in for a big line of broken computers in the next little while. Consumers have whittled the bottom line out of computer parts so badly, we return up to about 10% of even Asus boards at my shop now. It's expected when said Asus board costs only about $80, and the "equivalent" bottom of the barrel PC Chips board is about $60. The latest motherboards are using thinner and thinner and cheaper and cheaper PCB substrate, which reminds me of the bad old 486 days.

It's to be expected when everyone thinks a PC should cost under $300.

As far as this thread is concerned, it doesn't really matter if you turn the thing off at night, honestly. If you have junk components they'll just fail, no doubt about it.

As far as more power to start up, honestly, the inrush current to fill the capacitors, etc, isn't going to last longer than a few milliseconds, and can't be more than about 15 Amps, by law. Even for a full second, that's about the same amount of power your computer would use over about 6 seconds.
posted by shepd at 11:14 PM on November 20, 2004

It makes me nervous when my laptop fan goes on and stays on for more than a few minutes. I turn it off at night to 'let it cool.' Am I crazy? Laptops overheat. It happens.
posted by bingo at 12:29 AM on November 21, 2004

Heat is the enemy of all electrical components. Keep your system cool enough, and you can leave it on all the time. Just about the only time I power-down is when I'm out of the house for a couple of days. Otherwise, a reboot here, a reboot there, but the power is basically always on.

The two components most likely to fail under constant use are your monitor and your power supply (the next in line, hard drives, are a distant third). If you monitor goes into suspend after a few minutes, you're fine. If you're computer is cool enough and dust/fur free, the power supply should last a few years.

Used to be that hard drives needed to have their read/write heads reset before shutdown to preserve their longevity and reduce the chance of data loss. When a drive spins up, the movement of the platters creates a very small air lift for the heads to glide on. Take away the power, and the heads drop on to the media. Power them up again, and you risk dragging the head against the platter, potentially scratching it. This was in the old days (anyone remember full-height 5 Meg drives?) The last drive I had to "park" (as it was called) was an old Seagate ST-225, half-height 20 Meg drive. Modern drives don't really have this problem.
posted by Civil_Disobedient at 3:04 AM on November 21, 2004

I've heard at least as much nonsense from "the IT guy at work" than from people who might be expected to be computer illeterate. A little knowledge is dangerous, and an advertizing blurb in Byte magazine from 10 years ago might have lodged itself in one's brain without knowing its origins or veracity.

The best way to knock the IT guy down, consistently, is simply "where did you read that?" (asked with the full intention to fact-check him)
posted by Space Coyote at 3:07 AM on November 21, 2004

Yeah, fire that IT guy. Wrong, wrong, wrong. I bet he also cleans monitors with Windex.
posted by Mo Nickels at 5:33 AM on November 21, 2004

why aren't you supposed to clean monitors with windex?
(I don't even clean mine at home, so heh)
posted by angry modem at 10:10 AM on November 21, 2004

Probably not LCD ones ;)
posted by abcde at 10:29 AM on November 21, 2004

Google groups on windex and monitors.

It really all depends on how old your stuff is. REALLY old monitors that were dirt cheap at the time (oh, say that 14" you got in 1990 for a song) probably are best cleaned with something milder to avoid ruining the anti-glare coating.

Of course, nobody uses that junk anymore, so wash away with windex if you think you're in the clear. Check your owners manual, though (/me decides to check his).

Look at it this way: A wrecked anti-glare coating is a good reason to return a monitor under warranty, and there's no way a sane manufacturer is going to tell you using windex voids your warranty. So any smart manufacturer today will not be making monitor coatings which are damaged by ammonia. But not everyone or every manufacturer is smart.

*HOWEVER* this only applies to CRTs. Laptop LCDs can be yellowed or worse by ammonia or other harsh solvents.

Worried people should probably use a more "organic" and lighter cleaner like vinegar and water, or perhaps very light soap (although that will leave streaks, so that's sorta pointless -- you may as well just stick with the vinegar and water).

Also, spray onto your cloth, rather than the monitor.

Whatever you do, don't clean your monitor with Isopropyl Alcohol.
posted by shepd at 10:36 AM on November 21, 2004

What I use to clean monitors is the eyeglass lens cleaning solution found in optical stores and the optical shops in Wally World, etc. It's a mild cleaner, non abrasive, and will work for anything likely to be found on a computer screen.
posted by pjern at 6:51 PM on November 21, 2004

I clean my laptop with the same cleaner I use for the windows of my house. Commercial, pressurized, glass foam. I have no idea what's in it, but it evaporates clean and doesn't leave streaks. Great stuff.
posted by five fresh fish at 8:30 PM on November 21, 2004

Especially don't clean monitors with a mixture of Windex and bleach.
posted by grouse at 8:22 AM on November 22, 2004

The energy usage is minimal and not really a good excuse for leaving a machine on. The time to start up if you use a dozen applications might be a little more noticable if your machine is old and slow. Power supplies do wear out, and cycling the power often does help to wear them down quickly, but once a day versus once a week isn't going to make a huge impact. I leave my work machine on 24x7 during the week and only power it down during the weekend or when I'm away. My homemachine I turn on and off. I've only had one bad power supply at home in ten years, and that was a cheapo emachine that wasn't worth much to begin with.
posted by inthe80s at 8:46 AM on November 22, 2004

I like the convenience of having my computer on; also, I can start things (downloads, defragmentation back in the old days, etc) and let them run overnight or when I'm out or whatever. On top of that, occasionally my computer will be the gateway for another computer (i.e. providing internet access to another), so it's just polite to keep it on.

All modern OSes have options to let your hard drives and monitor power down, and a mostly-idle computer with the monitor and drives off uses very little power.

I've kept my computer(s) on 24/7 since about, uh, the mid-to-late 90s, and I've never had anything bad happen because of it.
posted by blacklite at 9:33 AM on November 22, 2004

fff, I have the same stuff (Chrysler / Mopar glass cleaner "with ammonia", don't ask how I manage to get ahold of odd stuff like that), and I won't even use it on my regular monitors! :-)

If you've used it this long without yellowing the LCD panel, though, you're probably ok, though.
posted by shepd at 10:11 AM on November 22, 2004

Ah, let me go find the can, then... [wanders off]

Okay, it's "Sprayway glass cleaner." spraywayinc.com

Contains no ammonia. Does contain ethanol and butoxyethanol. I am not to eat it, and if I do I should call poison control.

I just found out that London Drugs carries it now, and at 1/3rd the price that the local glass shop charges.
posted by five fresh fish at 11:09 AM on November 22, 2004

« Older Stuff that Turkey!   |   Who should you fear when downloading TV shows? Newer »
This thread is closed to new comments.