iMac Starts Only in Safe Mode

Discussion in 'Mac Basics and Help' started by evangw, Aug 1, 2016.

  1. evangw, Aug 1, 2016
    Last edited: Aug 1, 2016

    evangw macrumors regular

    Joined:
    Feb 9, 2008
    #1
    I have a 2009 iMac that suddenly starts only in safe mode — if I try to start normally, then the computer hangs forever (10+ min at least) on a grey screen after the apple shows up and the loading bar goes by.

    I have both a USB SSD (with 10.10.5) and an internal HDD (10.10.4) hooked up to it, and both startup disks give the same problem. The OSX installs on each are unrelated — the SSD was rescued a few months ago from someone else's broken Macbook Air, and I've used it since as my primary boot disc because even at USB 2 speeds it's faster than the internal drive for starting applications etc. I have not installed any software on the computer recently, and hadn't even used the internal HDD's system boot in about 6 months prior to this. In any case, both drives start fine in safe mode.

    Since it's not a harddrive issue, and not an obvious software problem, any other ideas? Is there some way it could be hardware? I don't really know what Safe Mode turns off. The most likely thing I've found online is that maybe it's a GPU issue? I'm not sure how to diagnose that without dragging the iMac into a not-really-nearby Apple Store.

    I have not notice any issues recently with this computer, which I use occasionally as a backup desktop.


    Edit: I suspect the problem is a busted graphics card, as per https://discussions.apple.com/thread/4975517?start=15&tstart=0 . I did NOT however have the problems these guys mentioned: http://forums.macrumors.com/threads...issue-screen-video-only-in-safe-mode.1958929/ so I only think it's a busted graphics card because I have no better ideas.

    the problem is, I do not see any files—at all—in /System/Library/Extensions in single user mode, which is odd, and "locate AMD*" or "locate ATI*" also do not find any files. Which is ... very odd. My computer crashed in the middle of listening to music, so it was not an issue that happened after a reset. I can't imagine where all my kexts went. When I type "locate *kext" then it shows me all these files in /System/Library/Extensions but ls /System/Library/Extensions is blank.

    Reinstalling the latest Yosemite from the apple store, just in case it is a software issue that affected both drives (can't imagine how that happened unless I downloaded an evil applescript that rm -f'd my /System/Library/Extensions in BOTH drives though, which sounds extraordinarily unlikely... and would have required my admin password, which I definitely would not type in when opening a 'PDF' or whatever)
     
  2. JohnDS macrumors 65816

    Joined:
    Oct 25, 2015
    #2
    Start in safe mode. Go to the Users Prefs panel. Create a new admin user. Shutdown. Reboot into the new user. If it boots all the way, then the problem is a startup item in your original user profile.
     
  3. supermariofan25 macrumors regular

    supermariofan25

    Joined:
    Feb 7, 2011
    #3
  4. evangw, Aug 2, 2016
    Last edited: Aug 2, 2016

    evangw thread starter macrumors regular

    Joined:
    Feb 9, 2008
    #4
    Thanks SMF! Unfortunately it looks like the D / option-D command does not work for 2009 iMacs (which I never knew about -- thanks), so you need the original install DVDs. I've moved 5 times since getting that computer, so I have no idea where they are, if I even still have them.

    In any case though, moving my AMD and ATI kexts to "Extensions_Disabled" worked, and now the system starts up, so it seems the the problem is indeed a busted graphics card.

    Any idea if it's 'safe' to use my computer with the graphics card permanently off? I wasn't sure if that will strain the processor or overheat or anything — I guess it shouldn't, but it's maybe not something that's normally stress tested. I mostly only use this computer as a file server, so it'd be great if I could get it to limp along until (if) Tim Cook realizes that most of the current mac lineup is hopelessly out of date. Although I guess it might need to limp along for years if my dream of a new Mac Mini is to come true...
     

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