iMac turned itself on after power was cut












6














I left my computer sleeping but turned off the power by accident. Hours after the power was turned back on the computer booted itself up. It is plugged into a UPS. I don't understand how this could happen.










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  • Is the "start on power" selected in the system preferences? if so it will start on getting power...
    – Solar Mike
    2 days ago










  • December 30, 2018. Skynet becomes self aware.
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    2 days ago
















6














I left my computer sleeping but turned off the power by accident. Hours after the power was turned back on the computer booted itself up. It is plugged into a UPS. I don't understand how this could happen.










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Debra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • Is the "start on power" selected in the system preferences? if so it will start on getting power...
    – Solar Mike
    2 days ago










  • December 30, 2018. Skynet becomes self aware.
    – Terminator
    2 days ago














6












6








6







I left my computer sleeping but turned off the power by accident. Hours after the power was turned back on the computer booted itself up. It is plugged into a UPS. I don't understand how this could happen.










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I left my computer sleeping but turned off the power by accident. Hours after the power was turned back on the computer booted itself up. It is plugged into a UPS. I don't understand how this could happen.







imac






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edited 2 days ago









wizzwizz4

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1086






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asked Dec 31 '18 at 7:33









Debra

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Debra is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






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Check out our Code of Conduct.












  • Is the "start on power" selected in the system preferences? if so it will start on getting power...
    – Solar Mike
    2 days ago










  • December 30, 2018. Skynet becomes self aware.
    – Terminator
    2 days ago


















  • Is the "start on power" selected in the system preferences? if so it will start on getting power...
    – Solar Mike
    2 days ago










  • December 30, 2018. Skynet becomes self aware.
    – Terminator
    2 days ago
















Is the "start on power" selected in the system preferences? if so it will start on getting power...
– Solar Mike
2 days ago




Is the "start on power" selected in the system preferences? if so it will start on getting power...
– Solar Mike
2 days ago












December 30, 2018. Skynet becomes self aware.
– Terminator
2 days ago




December 30, 2018. Skynet becomes self aware.
– Terminator
2 days ago










1 Answer
1






active

oldest

votes


















7














On the iMac, there's a setting under System Preferences > Energy Saver called Start up automatically after a power failure, which I'm guessing will be selected on your system, and hence would explain your computer's spontaneous rebooting.



If you don't wish this to happen in the event of a power failure, or the next time you turn off the power by accident, then uncheck that particular option.



Energy Saver Preferences on macOS, SierraNote: Screenshot taken on macOS 10.12.6 (Sierra)



As Tetsujin very helpfully points out in the comments below, there is also a button in the bottom right of the Energy Saver preferences pane labelled "Schedule...", which allows the user to regulate when the computer starts up, wakes up, or goes to sleep. It would be wise to double check your settings there too.






share|improve this answer



















  • 1




    There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
    – Tetsujin
    2 days ago






  • 1




    Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
    – CJK
    2 days ago






  • 1




    There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
    – Tetsujin
    2 days ago










  • @Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
    – Solar Mike
    2 days ago











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









7














On the iMac, there's a setting under System Preferences > Energy Saver called Start up automatically after a power failure, which I'm guessing will be selected on your system, and hence would explain your computer's spontaneous rebooting.



If you don't wish this to happen in the event of a power failure, or the next time you turn off the power by accident, then uncheck that particular option.



Energy Saver Preferences on macOS, SierraNote: Screenshot taken on macOS 10.12.6 (Sierra)



As Tetsujin very helpfully points out in the comments below, there is also a button in the bottom right of the Energy Saver preferences pane labelled "Schedule...", which allows the user to regulate when the computer starts up, wakes up, or goes to sleep. It would be wise to double check your settings there too.






share|improve this answer



















  • 1




    There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
    – Tetsujin
    2 days ago






  • 1




    Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
    – CJK
    2 days ago






  • 1




    There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
    – Tetsujin
    2 days ago










  • @Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
    – Solar Mike
    2 days ago
















7














On the iMac, there's a setting under System Preferences > Energy Saver called Start up automatically after a power failure, which I'm guessing will be selected on your system, and hence would explain your computer's spontaneous rebooting.



If you don't wish this to happen in the event of a power failure, or the next time you turn off the power by accident, then uncheck that particular option.



Energy Saver Preferences on macOS, SierraNote: Screenshot taken on macOS 10.12.6 (Sierra)



As Tetsujin very helpfully points out in the comments below, there is also a button in the bottom right of the Energy Saver preferences pane labelled "Schedule...", which allows the user to regulate when the computer starts up, wakes up, or goes to sleep. It would be wise to double check your settings there too.






share|improve this answer



















  • 1




    There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
    – Tetsujin
    2 days ago






  • 1




    Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
    – CJK
    2 days ago






  • 1




    There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
    – Tetsujin
    2 days ago










  • @Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
    – Solar Mike
    2 days ago














7












7








7






On the iMac, there's a setting under System Preferences > Energy Saver called Start up automatically after a power failure, which I'm guessing will be selected on your system, and hence would explain your computer's spontaneous rebooting.



If you don't wish this to happen in the event of a power failure, or the next time you turn off the power by accident, then uncheck that particular option.



Energy Saver Preferences on macOS, SierraNote: Screenshot taken on macOS 10.12.6 (Sierra)



As Tetsujin very helpfully points out in the comments below, there is also a button in the bottom right of the Energy Saver preferences pane labelled "Schedule...", which allows the user to regulate when the computer starts up, wakes up, or goes to sleep. It would be wise to double check your settings there too.






share|improve this answer














On the iMac, there's a setting under System Preferences > Energy Saver called Start up automatically after a power failure, which I'm guessing will be selected on your system, and hence would explain your computer's spontaneous rebooting.



If you don't wish this to happen in the event of a power failure, or the next time you turn off the power by accident, then uncheck that particular option.



Energy Saver Preferences on macOS, SierraNote: Screenshot taken on macOS 10.12.6 (Sierra)



As Tetsujin very helpfully points out in the comments below, there is also a button in the bottom right of the Energy Saver preferences pane labelled "Schedule...", which allows the user to regulate when the computer starts up, wakes up, or goes to sleep. It would be wise to double check your settings there too.







share|improve this answer














share|improve this answer



share|improve this answer








edited 2 days ago

























answered 2 days ago









CJK

2,658114




2,658114








  • 1




    There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
    – Tetsujin
    2 days ago






  • 1




    Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
    – CJK
    2 days ago






  • 1




    There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
    – Tetsujin
    2 days ago










  • @Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
    – Solar Mike
    2 days ago














  • 1




    There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
    – Tetsujin
    2 days ago






  • 1




    Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
    – CJK
    2 days ago






  • 1




    There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
    – Tetsujin
    2 days ago










  • @Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
    – Solar Mike
    2 days ago








1




1




There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
– Tetsujin
2 days ago




There's also the Schedule, bottom right, which could potentially explain why it switched on hours later.
– Tetsujin
2 days ago




1




1




Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
– CJK
2 days ago




Thanks @Tetsujin. I misread the OP as saying "Hours_later_, the power was turned back on...". I'll add your comment to the answer, as it's a very pertinent detail.
– CJK
2 days ago




1




1




There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
– Tetsujin
2 days ago




There is also the remote possibility that the UPS spent the first few hours recharging before pushing power to the Mac, but I don't know enough about UPS to know if that's a valid suggestion.
– Tetsujin
2 days ago












@Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
– Solar Mike
2 days ago




@Tetsujin yes, for a ups that can happen - depends how it can be configured... sure the answer will get updated to include that...
– Solar Mike
2 days ago










Debra is a new contributor. Be nice, and check out our Code of Conduct.










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