iMac restarts in the middle of sleep mode

Discussion in 'iMac' started by TherealDDX, Dec 4, 2013.

  1. TherealDDX macrumors member

    Oct 14, 2008
    Prague, Czech Republic
    Hi people of this wonderful forum. I've been having a weird issue that I tried to track down for quite some time already, but I haven't been able to find a solution, nor I managed to find any thread of anyone having the same problem, so I decided to try my luck here.

    My trusty 27" 2.93 Core i7 Mid 2010 iMac started to restart randomly about a year ago. Maybe not exactly randomly – sometimes it restarted itself sometime during the sleep process, usually in the middle of the night. It NEVER did that on any other occasion (under load, when waking up.. nada). I saw it a couple of times when I happened to be awake - sounds like it's about to start up, but it shows the grey startup screen and plays the chime instead. It was rare in the beginning, but the frequency kept increasing to almost once a day.

    Since the computer was already generally slow due to software bloat, when Mavericks came out I decided to take the pragmatic approach and reinstall the system clean to speed things up and possibly rule out a software problem causing these restarts. It worked great for about a week but then it appeared again. It restarted itself in total of 5 times since the reinstall. I saved all logs from the events:

    I tried running the Apple hardware test in the "extended" (or whatever it's called) mode resulting in no errors (I upgraded the ram to the 16GB kit by OWC, though).

    I'd appreciate any help by anyone able to dig through the logs.
  2. Twimfy macrumors 6502a


    Sep 11, 2011
    This was happening to me so I invested in a surge protector. Turns out it was the water heater in my house kicking in (it causes the lights to dim) and somehow this triggered the restart if a power failure occurs option (which to be fair I could have turned off).

    Not saying it's the same issue but it's worth a try.

    The Apple chime in the middle of the night used to scare the hell out of me.
  3. TherealDDX thread starter macrumors member

    Oct 14, 2008
    Prague, Czech Republic
    Thanks for your reply. I have this option turned off and I've been also experiencing some brief power outages recently which just left the computer turned off. These restarts seem to be caused directly by some kernel panic.
    Yeah, a surge protector or maybe some UPS is definitely on my list ;)
  4. DeltaMac macrumors G3


    Jul 30, 2003
    Your system.log would likely be more help than the crash log.

    I'm no great expert on perusing log files, but it looks like it's always a crash related to some USB device.
    What exactly do you have plugged in to USB?

    If there have been power problems recently, maybe you have an older USB hub that is not playing well with your power.

    A possible scenario to consider for troubleshooting: Your external USB bus is OFF during sleep, and very short power glitches (milliseconds) causing some external device to power back on for a very brief interval, causing your Mac to wake up, and the USB device (whatever it is) returns to OFF, because the Mac hasn't brought the USB bus on-line, and the "in-between" power causes a crash, with an automatic reboot due to the crash.
    And, a recommendation: If your house power is temporarily unstable, you should consider turning your computer OFF, rather than sleeping when not in use - at least until power settles down - or you add a UPS.
  5. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Do you still have the old memory modules? If so, put them back in and remove the OWC chips and see what happens.
  6. smithrh macrumors 68020


    Feb 28, 2009
    If it's power related, you'll need a UPS, not a surge protector.

    Also - need the system logs as someone else mentioned.
  7. TherealDDX thread starter macrumors member

    Oct 14, 2008
    Prague, Czech Republic
    Thanks, guys. I also noticed the string "IOUSBFamily" appearing repeatedly in the crash logs, and I do indeed have an older externally powered USB hub with a secondary mouse and a backup drive connected to it.
    Also maybe worth noting that sometimes I get a notification about this backup drive not being properly ejected after the mac wakes up (but it always appears as mounted).

    So I disconnected the hub and connected the drive directly for now. I'll see what happens.

    I grabbed system.log from about the time of the latest reported crash here:
  8. TherealDDX thread starter macrumors member

    Oct 14, 2008
    Prague, Czech Republic
    Hi guys, it's me again. I decided to re-investigate on the issue.

    So sum up what I've done:
    • Since the crash log kept pointing on the USB device, I removed my old USB hub which fixed the weird USB backup disk forced unmounting behavior, but not the crashes.
    • After connecting it directly to the computer, I removed the USB drive completely as it seemed to start up randomly, which could have some connection to this. Looks like it doesn't.

    The computer keeps crashing in the same circumstances (sleep mode, randomly during the night, never under load). There are some things changed in the logs, though:

    In the crash log, the "Kernel Extensions in backtrace" changed from the USB device to ""
    Full log:

    In the system.log the only activity during the sleep mode seems to be constant attempts to reconnect to my network drives (the "Volumes/Backup Disk," "Volumes/Media" etc. in the log) which reside in a Linux box as an AFP share. Could it be Time Machine trying to reach the network backup disk?
    Full log:

    So I decided to further troubleshoot this by disabling "Wake for network access" and I'm gonna try to unmount all network drives before letting the computer sleep.

    Do you have any suggestions, ideas about what might be going on? I'm running clueless here and it drives me nuts.

    Thanks for your time.
  9. rockboy macrumors newbie

    Jun 3, 2009
    Charlotte, NC
    Me too

    I would be very interested in feedback on this issue, as I am having the same problem with my 2.7 GHz i5 iMac restarting every night if I don't keep Jiggler running. I do have a couple of older USB hubs and ~3 year old USB external drives attached.

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