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  1. #1
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    IMac Randomly Shutting Down


    Three different times now, my imac has shut down for no reason. The first time was back in august. I took it to the genius bar, about an hour away. They ran a scan, and could not find anything wrong.

    The guy said they have an auto shut off if there is a surge and after about an hour or so, they will power back up.


    Mid November, i came home and it had shut down while my wife was on it. it had been down for a couple of hours and powered back up.

    As i type this, it's down once again. It's been down a Hour and a half. I am on my son's Christmas PC!


    Has anyone ever had this problem? Ever hear of it?

    Is there some type of systems test i can run on it when it finally powers back up?

    I bought it this past January - just about a year old.

    thanks!

  2. #2
    IMac Randomly Shutting Down
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,183
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    Mac computers are designed to shut down if they overheat. This is of course to prevent damage to the CPU and other components. I don't know if that's what your iMac is doing as there are other things that can cause a shutdown. Power supply, or bad memory for example.

    Before doing anything else... if your iMac is still under warranty or if you have apple care, take it on back to the genius bar and have them go over it again. Since it's so close to Xmas, it may be difficult to get an appointment right away.

    In the meantime, you might want to monitor the temperatures inside your iMac and the rotational speed of the fans. You can download istat menus from here or smcFanControl from here.

    Also, check your system logs when the shutdown occurs to see if there is anything that stands out.

  3. #3
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    Thanks for the repy -

    I don't think it's the power supply. I use surge protectors. I know that isn't the end all of protection, but it's a good start. Nothing else that has been plugged into the same protector has failed, or even wavered.

    I have plugged it into one of it's own for now.

    Never thought about it overheating..i have been on it all day. It doesn't explain the other times, but you could be on to something.

    Thanks for the links.

    I hate extended warranties, and never but them, but 2 days ago i bought one for the computer through my credit card company. It was cheaper and longer lasting coverage than offered by apple.

    The apple guy tried to sell it to me when i went down. It has been in the back of my mind ever since. As it was coming up on a year and it had shut down twice i bit the bullet.

    I hate the fact that the bar is an hour away, but that is how it goes. It would be after Christmas for sure before i could get it in.

    thanks again - if anyone else has any suggestions, i'm open

  4. #4
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    It's worse than thought.

    It never restarted last night, and will not boot up this morning. Is there any way to get it started besides the button on the back?

  5. #5
    IMac Randomly Shutting Down
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,183
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    When you say it "never restarted", are you getting anything at all on the screen? Can you hear the fans spinning? Or is the machine completely dead - no power whatsoever?

    If it's completely dead - no power - that's indicative of a bad or failed power supply. Which may be the reason for the random shut downs you were experiencing.

  6. #6
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    Quote Originally Posted by chscag View Post
    When you say it "never restarted", are you getting anything at all on the screen? Can you hear the fans spinning? Or is the machine completely dead - no power whatsoever?

    If it's completely dead - no power - that's indicative of a bad or failed power supply. Which may be the reason for the random shut downs you were experiencing.
    no power at all - no fan, nothing on screen.


    when you are talking about ther "power supply" you are talking about where the computer is plugged in, correct?

    nothing else coming out of the outlet has failed. i just now tried a different outlet, the fan kicked on for about 2 seconds, then went down. nothing ever came up on the screen.


    it's obvious it's the computer - it's been almost 24 hours, the fan coming on a minute ago was the first sign of life.

  7. #7
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    some good news - i just called the apple store. they take appointments early. my wife has some minor surgery monday. they can get me in before her surgery.

    i'm almost hoping it doesn't fire back up - at least they can see what the problem is.

    the other good news - it will be in under apple's warranty, that goes out jan 5!

    i'm glad i got the extended now. i am hoping they can find what is wrong, but if not i'm covered for 4 years.

  8. #8
    IMac Randomly Shutting Down
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,183
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    Thanks for posting back. Let us know how it goes with Apple and have a Merry Christmas.

  9. #9
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40
    Quote Originally Posted by chscag View Post
    Thanks for posting back. Let us know how it goes with Apple and have a Merry Christmas.

    merry christmas to you also!

    thanks for trying to help, i really appreciate it. i'll keep you guys updated.

  10. #10
    IMac Randomly Shutting Down

    Member Since
    Jan 10, 2010
    Posts
    40


    got it back today - i just plugged it in - up and running. the power supply went bad.

    in monday, out thursday.

    i am a happy snob again

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