Leaving a mac powered on for a long time

Hi, is there any risk to leaving a mac powered on for a long time?

I’m specifically wondering if there is risk in keeping a 2019 mac pro powered on for several days or weeks consecutively. Would that be completely safe or would that be a risk to the hardware and/or a fire hazard?

I know that the 2019 mac pro comes in a server model, but I’m most curious about the 2019 mac pro that stands up vertically. When I’m not using it, the displays would be off and the computer would be in the lock screen. I don’t have much experience with servers or leaving computers on for a long period of time and the idea of leaving a computer on for a long time makes me a bit nervous that something could go wrong while I’m sleeping. It seems like it’s not a large risk because I know that many people run many servers overnight without issue, but I’ve never done it before and want to make sure that everything would be safe and the hardware would not get damaged.

I’m also wondering the same thing about macbooks. Do you think there any risk to leaving a 2012 macbook pro powered on for several days or weeks consecutively?

Also, is there anything that I should be aware of or do differently to make sure that it is safe? Or certain rules or protocols to follow? For example, would it be a good idea to periodically turn the computer off to give it time to rest?


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There is effectively zero risk in leaving a desktop or server permanently plugged in. You don’t need to worry.

For the laptop, I’d worry about degrading the battery, so I would periodically look at the battery health with an app like Coconut Battery, and periodically check for signs of battery bulging. However, I wouldn’t worry about a fire or electrical damage.


My iMac and Mac mini never get turned off and only get rebooted for software updates. The mini doesn’t even sleep. No issues.


Ok awesome, thank you!

To hone in on one detail - you wrote that there is effectively zero risk in keeping it permanently plugged in, but does that mean there is effectively zero risk in keeping it permanently powered on?

I’ve almost always leave my computer plugged into a surge protector or UPS for a long time, but usually click the “shut down” button in the menu bar to turn the computer off at night. I want to make sure that it’s safe specifically to leave the computer powered on so that I don’t hit the “shut down” button at night and it is not only plugged in but there’s a small light on the computer that’s always on and it’s always ready to be used without needing to boot it up to the apple loading screen. I think this might be semantics judging from Chris’ response but want to make sure I’m understanding correctly.

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My iMac Pro has been on for about 22 months now, except for power failures.
There should be no reason to turn your machine off.

The only reason I can think of powering down at night is if you were in an industrial environment like a sewing factory that has lots of lint and dust in the air. Leaving the machine on would mean it would need to be cleaned more often. But again, that’s not a common case.

Oh, perhaps also if you were using solar power and had to watch ever Watt of electricity used.


I shutdown my Mac once a week. I think the longer the OS is running the greater chance there is for a rogue process to have a memory leak or go into an endless loop and consume resources. Maybe once a week is too often, but never shutting your Mac down is probably going to lead to trouble at some point.

I think servers are a different animal. They mostly don’t run a GUI and are monitored more closely for problems. But even in that case I would recommend shutting down and rebooting periodically.


With the exception of updates, etc. I had a 2011 Mac mini running 24x7 for around 7-8 years.


Ok great, thanks so much! I never realized it was so common and safe to leave a mac on for a long time, that makes me feel a lot better about it and also saves a lot of time!

One other thing that just came to mind is the sleep and energy saver settings. In my mac’s settings, the options for "Put hard disks to sleep when possible” and "Enable Power Nap” were enabled and the option for “Prevent computer from sleeping automatically when the display is off” was disabled.

I think that I would like to reverse these settings, so that "Put hard disks to sleep when possible” and "Enable Power Nap” are disabled and “Prevent computer from sleeping automatically when the display is off” is enabled (as shown in the screenshot). I’m not exactly sure what all these settings do, but I think that some of these sleep and power nap settings might interfere with some processes that the mac is running.

Would it still be just as safe to leave the mac powered on if I changed these three settings (so that the computer and hard disks do not go to sleep or power nap)? Or would changing these settings introduce additional risk?


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I allow the iMac to go to sleep when display is off. I can’t think of a problem that causes. So, my settings are:

: Prevent computer … unchecked (and I have display time out as 2 min)
: Put hard disks to sleep … unchecked (I have SSD and not hard disk, for what it’s worth)
: Wake for … checked on (sometimes I do a remote login)
: Start-up automatically … checked on
: Enable Power Nap … checked on (but I suspect without total knowledge that sometimes machien comes out of sleep and does not go back into sleep after whatever it decided to do was done)

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I’ve never been concerned about leaving them on. When I used a MacBookPro almost every workday I only turned it off on weekends. The desktops are set to sleep when not in use except for the server which is always on. Here’s an interesting snapshot showing uptimes:

My iMac is on top, the server Mac mini (up 107 days 24/7 full on) is second. It has been running 24/7 for about 6 years. Two entertainment minis (also used to run 32 bit software) have been up 38 and 54 days respectively. That last mini is 11 years old.


I don’t know if this is about powering up/down the hardware. Or rebooting.

With a MacBook Pro I rarely do either. Probably one should power off on a Friday evening to:

  1. Reboot without any eg leaked memory objects, handles etc.
  2. Reset your brain :slight_smile:

Thank you everyone, that’s very helpful!

The one thing I’m still not sure about is if it would be safe to turn off all of the sleep and power nap settings (as shown in my last post) or if that would add more risk.

tomalmy said that his server Mac mini was on at all times without sleeping, but I’m wondering if it would be safe to do this if the computer was not a server. My Mac would be used as a desktop with a GUI, not a server (though the displays would be off and it would be in the login screen when not in use).

If I change the settings so that the computer and hard drive do not go to sleep or power nap, would that be bad for the computer or create any electrical risk?

Would it be a good idea to allow it to sleep or power nap every once in a while? If so, how often?

The only reason to consider sleeping the computer or the disks is to save on electricity. It doesn’t matter if it’s a server or not.

You could run a desktop for years without letting it go to sleep.

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@cornchip is correct. My 2011 Mac mini had a spinning drive and still ran constantly for years. And most of the entry level iMacs I purchased for my company in 2009 were still in use when I retired 2 years ago. My users rarely turned anything off.

(Note: we ran Macs until they failed or no longer received security updates)


Another reason is light pollution. I already get quite enough stick for all the little indicator lights in my home office - across the landing from a significant bedroom.

I used to put black tape over the LED’s of the worst offenders. In my last appartment, I had a bedroom/office combo and I taped everything. Now, I have no electronics in my bedroom, so it isn’t a huge issue anymore. But the Mac mini “server” is still taped, also the router and other “always on” stuff.


Actually I think the process of spinning up a HDD is probably more stressful than just letting it cruise leisurely along while the machine is idle. Whether that’s true with SSD’s, I don’t know.


That’s a trade off between aesthetics and lights. If someone made little blackout stickers in square and round they’d make money.

My secret: a scissor.


Turning a computer on causes stresses with the power surge, and power cycling in general causes thermal stress. Leaving the computer on avoids all of this. Just hunch based, I’d say 90% or more of failures occur when turning on the power.