Leaving IMac on all the time: Why is it Hot?

Discussion in 'Digital Darkroom' started by jon_kobeck|1, Sep 17, 2012.

  1. So as advised here, I'm leaving my new iMac on 24/7 and its energy settings are set to default so it goes to sleep after a few minutes of
    inactivity, I. Otice even after sleeping all night, when I touch the top of the machine it's a little warm. Is this normal?
     
  2. Spearhead

    Spearhead Moderator

    Apple's implementation of the sleep functionality is bad enough that there is a utility that is often recommended to fix it. It's called Please Sleep and it's free. Works great, and has some terrific options, such as blocking sleep when certain applications are running.
     
  3. Apple systems run hot, and this is especially noticeable when they are new.
    You will find though at some point even Macs benefit from being turned off rather than sleeping them everyday.
     
  4. "Sleep" is not the same thing as "Off". Sleep has to keep things like memory and video RAM intact, needs to monitor the USB bus and/or BlueTooth for your wake-up call, so it still needs power. Thus, the power supply is running constantly, changing your AC power from the wall into the DC power all the internal bits require. This process does waste heat converting the AC to DC. In sleep, a lot less power is required, as the processor is idle, the hard disk(s) spun down, and the display is off. Also, the fan(s) are usually off, so it is depending on heat convection (hot air rising) and conduction (heat dissipation through the aluminum chassis) for cooling.
    If you are running Lion or Mountain Lion, unless you need to have the iMac turn on instantly (which, even from sleep, isn't so "instant"), or have an AppleTV that you stream stuff to from the iMac, you're just as well off shutting down the iMac. Lion and Mountain Lion let you restart to just where you were when you shut down. It's not like the "clean slate" you got in Snow Leopard and before, where you have to launch all your apps upon startup. You can come right back into your e-mail, Safari, Excel, etc.
     
  5. Spearhead

    Spearhead Moderator

    Apple systems run hot​

    An iMac that is asleep is not hot.
     
  6. So as advised here, I'm leaving my new iMac on 24/7 and its energy settings are set to default so it goes to sleep after a few minutes of inactivity, I. Otice even after sleeping all night, when I touch the top of the machine it's a little warm. Is this normal?​
    As Larry said, yes, it's normal. Even while it's asleep, it's still consuming power, which means the power supply is converting waste energy into heat, which the aluminum casing transmits quite nicely.
     
  7. Spearhead

    Spearhead Moderator

    Mine was cold this morning after being in sleep all night.
     
  8. I'm leaving my new iMac on 24/7 and its energy settings are set to default so it goes to sleep after a few minutes of inactivity​
    Ok. perhaps I'm not understanding. Is the iMac actually in sleep mode, or is just the display sleeping? If the "Computer sleep" slider is set to "Never", then the iMac is not sleeping, just the display is sleeping (and perhaps the hard disk/s).
    From your statement "after a few minutes of inactivity" it sounds to me like the display is sleeping, but not the whole iMac. The display consumes the lion's share (sorry...) of the power consumed by the iMac. But merely sleeping the display is not the same thing as sleeping the computer. Effectively, the iMac is still completely functional, up and running, but is conserving energy by not having the display on.
    I don't know anyone who'd set up their Mac to go completely to sleep after just a few minutes of inactivity, and especially not Apple in the default settings. A few hours, perhaps, otherwise, you'd sit back to watch a long YouTube clip, and the whole thing would shut off on you in the middle.
     
  9. Perhaps I'm just old fashioned, but I feel that my iMac benefits from a periodical shut down and rebooting. I usually turn it off when I know I'm not using it for 8 or so hours.
    Although I leave my laptop pretty much on 24/7 (though closed up in sleep mode), it too seems to benefit and run better with the occasional restart.
    I've got Lion on both of these.
     
  10. An iMac that is asleep is not hot.​
    So it was likely not actually asleep. There are multiple settings available in the 'Energy Settings' control panel, just because the display is dark doesn't mean the system is actually 'sleeping'. Unless those are checked, and set appropriately sleep may not actually be happening.
    However as well as it works I still think sleep on the Mac is not the best practice.
    The iMac construction has the whole computer inside that monitor case so when it runs it is going to be at least a bit warm to the touch. There's no fan in it that I know of, and the internal heat will rise to the top of the unit while running.
     
  11. There are several fans (number varying by model and size) and the system runs well within the operating specifications of its components.
     
  12. Perhaps I'm just old fashioned, but I feel that my iMac benefits from a periodical shut down and rebooting. I usually turn it off when I know I'm not using it for 8 or so hours.​
    I completely agree! I've yet to meet ANY operating system (with the possible exception of Solaris...) that does memory management and garbage collection well enough that it didn't need a reboot on occasion. I even do it with my iPhone & iPad, even though everyone says it's unnecessary.
    I try to keep my MacBook Pro (and four external drives, and 23" Cinema Display, and...) off when I know I won't be using it for more than a day.
     
  13. rnt

    rnt

    There's a school of thought (that I tend to agree with) that says that thermal stress caused by turning the computer on and off can be a problem.

    Once upon a time, if you had a Windows box, remembering to reboot periodically wasn't an issue- it would do it for you :) On the other hand, I had a linux server stay up for a year and a half (not necessarily recommended) with no apparent ill effects. It finally went down after a long power outage.

    As a part time systems manager I attributed most of my success to never rebooting unless absolutely necessary- and never after noon on Friday!
     
  14. Steve jobs notoriously hated fans and the perceptible hum/whine noises that most Wintel machines make.

    My iMac is on all the time and only until this summer's heat wave in Southern California (102°-112°...unbelievable for here) did I ever experience an above normal range of heat dissipation problem, which actually gave me freaky screen effects from the overheated GPU and Video Card.

    Solution: There are a variety of apps available that can raise the speed of the 3 internal fans on a Intel-iMac, and can be set to any speed and internal temperature you desire with a corresponding increase in the noise of the fans from inaudible to annoying.

    Beware, the first time you crank them up, accumulated silicon dust bunnies come flying out! I have been using this one for 2 months now with absolutely no damage to the iMac and it can be reset to the default fan settings anytime.

    http://www.derman.com/iMac-Fan-Control
     
  15. When my iMac sleeps it doesn't get warm.
     
  16. Unlike the windows rubbish, I-Macs are designed to be left on. It's in their genes so to speak. It's the very nature of that self-monitoring framework and the fact that they have a structure based around the server monitoring framework, unlike microsoft windows which is full of inter-dependent software, (ie, if one goes so does another 20% get issues that have to be resolved before the one that failed can actually be sorted out); not so the mac, all its parts are independent, and logically arranged. The mac benefits from being left on, I switch mine off about once every three weeks, sometimes four weeks and it is 5 years old. The extra heat can be generated by something working very hard under the hood that should not be. I also had this issue once and I could not understand why it was heating up even when there was no activity. So I did a major clean up and shut down, and this oddly solved the problem for about two years, then it happened again for about two weeks, so, after a clean up of system caches (not to be performed unless of emergency), and various other things that I would not normally clear out, I shut down the computer for 24 hours and since then it has not happened. That was a year ago.
     
  17. Spearhead

    Spearhead Moderator

    The iMac construction has the whole computer inside that monitor case so when it runs it is going to be at least a bit warm to the touch. There's no fan in it that I know of, and the internal heat will rise to the top of the unit while running.​

    As other people have pointed out, the comment about fans is dead wrong. Regarding the first sentence, this is true of every laptop regardless of OS or brand.

    There is a simple way to tell if a Mac is in full sleep or not. If the login screen comes up immediately, then only the monitor is asleep. If it takes at least a couple seconds, the computer was asleep.
    Unlike the windows rubbish, I-Macs are designed to be left on.​
    This is ancient rubbish. My wife has a Windows machine for her work, I sometimes have to help her with (non-system) things, and it has been on for months at a time without a problem. Windows 7 seems to be far more capable in this respect than past versions.
     
  18. Regarding the first sentence, this is true of every laptop regardless of OS or brand.​
    Your laptop maybe but not mine.
     
  19. Spearhead

    Spearhead Moderator

    Your laptop doesn't have the whole computer in its case? It's got some sort of tether to the electronics?
     
  20. "There is a simple way to tell if a Mac is in full sleep or not. If the login screen comes up immediately, then only the
    monitor is asleep. If it takes at least a couple seconds, the computer was asleep"

    I have an SSD so it comes up almost instantly. That's a hard one to use
     
  21. I found that if I could make my iMac (mid 2007) properly sleep it was barely warm, and only consumed a few watts. I
    have also found that in order to make it properly sleep (not just the screen off) then I have to quit safari before sending
    it to sleep.
     

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