Imac - leave on or swith off? does it cause problems? what do you do?

I've just bought a lovely used 20" ali imac and the apple booklet says to keep it switched on in between use, or switch off if not being used for several days.

It seems a silly question but is there any disadvantage to leaving the imac on and asleed regularly when not in use, eg, overnight? will the fan be running? I know the biggest shock to a system is switching on but are there any disadvantages to leaving it asleep for hours at a time? What do you do?

thanks for your thoughts! Alan

I do what you state Apple recommends "the apple booklet says to keep it switched on in between use, or switch off if not being used for several days."

I switch my Imacs off every time I know I won't use it for several hours. I never had problem doing it (> 10 years on mac and > 5 years on my imac). Save Power, switch it off.
--
http://www.nosenzor.fr

Likewise, mostly because I like to switch off the mouse to save batteries and you can't do that once the computer is asleep without waking it up. So I just shut down every night.

Alandprev said:

It seems a silly question but is there any disadvantage to leaving the imac on and asleed regularly when not in use, eg, overnight? will the fan be running?

Click to expand...

There is no fan in sleep mode. The only thing different is the electricity consumption, switched off you are at zero (or very close, who knows about the power supplies), in sleep mode it does use a little bit of power.

The advantage is if you have 30 applications and 50 windows open, waking up from sleep takes one second. Booting and opening all applications and windows takes maybe three minutes.

I've been leaving mine on between uses for the last ten years without any issues. I just leave it to sleep, or shut it down if it's not going to be used for more than 24 hours.

There are two ways to look at it. As you say, the most stress is during a cold startup, as well as the biggest current draw (electric circuits have more resistance when cold). This can cause stress to chips and components as they draw current to warm up.

However, the other side is, that keeping it running, and warm, is also using power when it's idle (the heat is wasted energy), and there's going to be degradation of the components anyway.

Either way, there isn't a right answer ecologically or economically, one way uses more energy, and the other may shorten the life of the product (requiring an earlier replacement).

I believe that current statistics show that there's really little difference in longevity between the two methods, so it's really just down to you're own preference/circumstances.

I think the main reason it is recommended to be left on, is that OSX (being Unix based), works better if left running, as it tends to 'settle' down, builds caches, and runs maintenance routines during idle time that obviously won't run if it's off. A quick logout/login is often sufficient to clear any performance problems.

Just my 2¢ worth.

--
Andy Hewitt

Thanks for the interesting comments. One concern I had was whether the fan would run sometimes during sleep, which might shorten the life of the fan. However, I had not considered that as the electrical components will remain warm when the imac is sleeping that too will shorten its life.

Alandprev said:

Thanks for the interesting comments. One concern I had was whether the fan would run sometimes during sleep, which might shorten the life of the fan. However, I had not considered that as the electrical components will remain warm when the imac is sleeping that too will shorten its life.

Click to expand...

Sleep is the same as off except that memory is maintained so it can wake instantly, and that consumes a negligible amount of power. Everything else is off (display, hard drive, CPU, GPU, etc.). The Mac does not stay warm and the fan won't ever come on either.

Andy Hewitt said:

I think the main reason it is recommended to be left on, is that OSX (being Unix based), works better if left running, as it tends to 'settle' down, builds caches, and runs maintenance routines during idle time that obviously won't run if it's off. A quick logout/login is often sufficient to clear any performance problems.

Click to expand...

Yeah, but they don't run in sleep mode either. Recent versions of OS X have switched control of these functions to launchd anyway, so they run at the first opportunity if the computer is off/asleep at the scheduled time.

if you don't use it for 8 hours per night you will save a lot of money turning it off.
See : http://michaelbluejay.com/electricity/computers.html or
http://kom.com/reviews/apple_power_consumption/

While in sleeping mode still consume at least 3 or 4W so you can save 12-15% of your imac electric day consumption by turning it off.

What i have learned also is that these computer also had a little consumption even while they are off !

--
http://www.nosenzor.fr

Nihao said:

if you don't use it for 8 hours per night you will save a lot of money turning it off.

Click to expand...

Not compared to sleeping it you won't.

Nihao said:

See : http://michaelbluejay.com/electricity/computers.html or

Click to expand...

You might want to read the links you cite.

"As long as your computer goes into sleep/standby when you're not using it, your computer doesn't use squat for electricity, compared to the rest of your household. You'll save a lot more energy by addressing your heating, cooling, and lighting use rather than obsessing over your computer."

"Setting your computer to auto-sleep is the best and easiest way to save on computer energy use!"

Nihao said:

http://kom.com/reviews/apple_power_consumption/

Click to expand...

From their measurements, the difference between sleep and off is typically about 1 watt. The cost of 1 watt of electricity over a year is a couple of dollars, at the most.

gaussian blur said:

Alandprev said:

Thanks for the interesting comments. One concern I had was whether the fan would run sometimes during sleep, which might shorten the life of the fan. However, I had not considered that as the electrical components will remain warm when the imac is sleeping that too will shorten its life.

Click to expand...

Sleep is the same as off except that memory is maintained so it can wake instantly, and that consumes a negligible amount of power. Everything else is off (display, hard drive, CPU, GPU, etc.). The Mac does not stay warm and the fan won't ever come on either.

Click to expand...

There will be some warmth there - there has to be! If the circuits are powered, which they'll also have to be if the memory is to retain its contents, it will produce some heat, albeit a very small amount while asleep.

--
Andy Hewitt

Conchita said:

Conchita said:

I think the main reason it is recommended to be left on, is that OSX (being Unix based), works better if left running, as it tends to 'settle' down, builds caches, and runs maintenance routines during idle time that obviously won't run if it's off. A quick logout/login is often sufficient to clear any performance problems.

Click to expand...

Yeah, but they don't run in sleep mode either. Recent versions of OS X have switched control of these functions to launchd anyway, so they run at the first opportunity if the computer is off/asleep at the scheduled time.

Click to expand...

Yes of course, nothing can run while it's asleep, but some operations also wait for idle time, which may not occur if you shutdown very soon after working.

--
Andy Hewitt

Andy Hewitt said:

There will be some warmth there - there has to be! If the circuits are powered, which they'll also have to be if the memory is to retain its contents, it will produce some heat, albeit a very small amount while asleep.

Click to expand...

It's negligible. As noted elsewhere in this thread, the power consumption is a couple of watts.

Andy Hewitt said:

There will be some warmth there - there has to be! If the circuits are powered, which they'll also have to be if the memory is to retain its contents, it will produce some heat, albeit a very small amount while asleep.

Click to expand...

If you care about these couple of degrees, you should probably put your computer out into a colder room over night.

I leave my two iMacs asleep rather than turn them off at night, unless I am leaving town and not using them for a few days. I also shut down and unplug my computers when we have a bad thunderstorm, even though I have everything plugged into decent surge protectors. We've had our intercom, TV's and garage door openers blown during a violent thunderstorm, and I just don't like to take a chance.

I'm the least techie person on this forum, so I just do what makes me comfortable.

I've had iMacs since the old Bondi-Blue days, and I've never had a problem with the sleep factor .

carolyn
--
Ranger a.k.a chammett
http://www.pbase.com/chammett

'elegance is simplicity'

noirdesir said:

Andy Hewitt said:

There will be some warmth there - there has to be! If the circuits are powered, which they'll also have to be if the memory is to retain its contents, it will produce some heat, albeit a very small amount while asleep.

Click to expand...

If you care about these couple of degrees, you should probably put your computer out into a colder room over night.

Click to expand...

I think you're missing the point. I'm not worried about the heat, only that the heat means that energy is being wasted. One point of leaving a computer running, is to minimise the thermal stress during a cold start, hence some heat is still being produced, which must mean energy is being used.

I never said it would be significant, unless you add up the power consumed in a large business (say, 100 computers, all using 2-3W), or an entire city perhaps. Then it does become significant.

It also might vary depending on the machine - my old dual G5 used 20-30W when asleep, and 300W at idle (running but no workload). My MacBook alone uses about 40W in use.

Also consider any peripherals that are connected, but may not be powered down - USB hubs, external drives, network devices, and so on.

I have one of those devices plugged in that monitors the power usage, so I know how much is being used at any time - with all the extra devices attached, it's using 124W at the moment, and drops to 51W when I sleep it (external hard drives still running, as they're permanently attached). Considerably more than the 2-3W quoted...

More testing, and it drops to 85W when I dismount and power down the hard drives. Taking it all to a minimum sleep mode, and it's at 16W. All that's powered up there is my sleeping MacBook and a USB hub.

--
Andy Hewitt

According to the info on Apple's website, their laptops and iMacs seem to draw about 1 watt more in sleep mode than when shut down. 1 Watt overnight, say 10 hours, is 10 watts per day saved. I don't know what the power costs are where you live but the average is about $0.12 per kwh so leaving it on overnight will cost you about $0.0012 cents per night more than shutting it down.

--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams

When the computer is running it may be in "sleep" mode but it still is consuming power and it is still able to be damaged by surges from your local power company. Don't expect a surge suppressor with a MOV to really protect your computer. Better to have the computer powered off and then turn off the power strip or UPS device.

It is estimated by the government that 75% of the power used by TV's in the USA is from standby power consumption and not from viewing. Same applies to PC's and their monitors. Do the planet and future generations a favor and don't waste power and add any more pollutants than are really necessary.

Easy to take a what me worry attitude and leave everything powered on for convenience but that is what got us where we are today with two wars for oil so I applaud your interest in doing the right thing.

calson said:

When the computer is running it may be in "sleep" mode but it still is consuming power and it is still able to be damaged by surges from your local power company. Don't expect a surge suppressor with a MOV to really protect your computer. Better to have the computer powered off and then turn off the power strip or UPS device.

It is estimated by the government that 75% of the power used by TV's in the USA is from standby power consumption and not from viewing. Same applies to PC's and their monitors. Do the planet and future generations a favor and don't waste power and add any more pollutants than are really necessary.

Easy to take a what me worry attitude and leave everything powered on for convenience but that is what got us where we are today with two wars for oil so I applaud your interest in doing the right thing.

Click to expand...

I call BS on this. Provide a link to back this up.

Here is what a current CNET study shows.

"It may surprise you to hear that TVs use power even when they're not turned on. So that the TV is ready to respond to the remote in an instant, all sets use what's called phantom or standby power. Our tests revealed that standby power consumption varied somewhat among different TVs, but in general newer models consume negligible power when turned off. Energy Star 3.0 (see below) requires power consumption of less than 1 watt in standby to qualify. To put that in perspective, leaving a TV that uses 1 watt in standby turned off for a year would cost just $1 at average 2008 energy prices."

I'll not comment on your delusional thoughts on wars. Lets just lets keep this thread non-political please.
--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams