Imac shuts down on sleep - set prevent sleep option?

[SamJames170]

I have Imac 10.11.6 El Capitan

I have phases where it shuts down on sleep and wont wake, I cant switch back on via rear button or any device activity it has basically shut down. If I switch off mains power for say 10 seconds then will re-start from back screen power button.

I have had this happen before and I get it for say a week then it somehow goes away for a month then might start doing it again.

If I tick prevent sleep in preferences energy settings what affect does this have on taxing my mac ongoing.

I will get a new mac in about a year so dont really want to upgrade software as this is a work computer with lots of installs and dont want to go to those lengths right now. Its very odd this only happens once in a while and is not a fixed problem !

Thanks if anyone can help.

Sam

 

[mystery hill]

If I tick prevent sleep in preferences energy settings what affect does this have on taxing my mac ongoing.

You can enable that option. It's not going to negatively impact your Mac.

It's just a power saving feature.

 

[Fishrrman]

If you're having "wake from sleep" problems, I'd say the easiest workaround is to set the iMac so that it NEVER sleeps on its own. (if possible)

Just put a screensaver on, or put the display to sleep, and leave the rest of the iMac "awake, but idling..."

 

[Nguyen Duc Hieu]

iMac with El Capitan...
Maybe the CMOS battery has drained out....
Just my guess.

 

[MacorNothing]

Maybe, one idea :

> Go on Applications > for Opening Utilitary > and registered on Terminal.

nohup caffeinate -dimsu & killall Terminal.

Prefer ask this to another member, I'm not sure, thanks U,
have a nice day