13 Replies Latest reply: Dec 11, 2012 5:53 AM by freulv
freulv Level 1 (0 points)

I'm having lots of strange hardware issues with my iMac 27. The system keeps crashing, so I decided that I wanted to check the system with the AHT, Apple hardware test. Following the instructions (to press cmd-D, or just D) after a system re-boot, (waiting for the start-up sound), just doens't do the trick. The computer boots up normally, it seems to take much longer time. but in the end I just get the log-on screen.


Any ideas how get into the hardware test?

iMac, OS X Mountain Lion (10.8.2)
  • sbriss Level 1 (100 points)

    Did you disconnect any devices attached to your Mac? If you have an Ethernet cable plugged, unplug it too before restarting. When does your Mac crashes? I mean using a particular application?...

  • Radiation Mac Level 5 (4,645 points)

    Did you specifically do  ALL of the following steps?:




    Use Apple Hardware Test

    1. Open the Help Viewer’s Action pop-up menu (looks like a gear) and choose Print to print these instructions.
    2. Disconnect all external devices except the keyboard, mouse, display, and speakers. If you have an Ethernet cable or external DVD drive, disconnect them.
    3. Restart your computer, holding down the D key while the computer restarts.After your computer restarts, you should see the Apple Hardware Test chooser screen. If you don’t, Apple Hardware Test may not be available on your computer. You may be able to start Apple Hardware Test from the Internet. Reconnect your computer to the network, and then restart your computer while holding down both the Option and D keys.
    4. When the Apple Hardware Test chooser screen appears, select the language you want to use, and then press the Return key or click the right arrow button.
    5. When the Apple Hardware Test main screen appears (after about 45 seconds), follow the onscreen instructions.



    Hope this helps


  • freulv Level 1 (0 points)

    I haven't been able to spot any particular application that causes the crashes, it's extremely frustrating.


    I followed all the steps, except printing the instructions, I have an iMac so I don't really have anythingconnected to it. Just my keyboard..

  • sbriss Level 1 (100 points)

    Maybe you can try to use Disk Utility to verify and repair permissions first and see if it still crash.

  • Linc Davis Level 10 (192,644 points)

    If the machine came with discs, you have to insert the one that has the AHT on it (as shown on the label.)

  • freulv Level 1 (0 points)

    I did the verify and repair permissions, but same result.


    It was pre-installed with Lion OS X, I have upgraded to Mountain lion over the web so I don't have any disks with this o/s. Is it still worth looking for the original disks?

  • Linc Davis Level 10 (192,644 points)

    There are no discs, if the machine shipped with Lion as you say it did. In that case you should be able to run the AHT by booting with the option-D key combination pressed. Did you try that? If you did, and the system booted as usual, what kind of keyboard are you using? If it's a wired keyboard connected to a USB hub, connect it directly to a built-in USB port and try again.

  • sbriss Level 1 (100 points)

    If you want to re-install Mountain Lion, here is what I suggest:


    - first create a Second Partition on your Hard Drive using Disk Utility


    - Restart your Mac using the Option key (you will be able to select the Mountain Lion Recovery disk) as your startup disk.


    - Then you'll be able to re-install Mountain Lion from there, on your second partition you created earlier.


    - Then if you want you can use Migration Assistant to transfer whatever you need from your original partition. But my concern with that is that if the crash is created by an application, there are chances that you have the same problem on your new partition.


    But it would be really helpful to know where the crash is coming from.

  • John Galt Level 8 (45,978 points)

    freulv wrote:


    ... The system keeps crashing,


    Just to be clear, does an application crash with a dialog box "The application ... has unexpectedly quit" or does the system crash as in a kernel panic, which requires that you shut down the Mac?


    Read the following for each respective event. Next time it occurs, post the crash report in a reply.


    Mac OS X: Relaunching an application after it unexpectedly quits (outdated but similar)

    Mac OS X: How to log a kernel panic


    Be sure you are holding the d key or option d (lower case d). Either one should work with both wired and Bluetooth keyboards.

  • noondaywitch Level 6 (8,135 points)

    post withdrawn; already answered above.


    Message was edited by: noondaywitch

  • freulv Level 1 (0 points)

    It's a mix of kernal attacks and that the computer just freezes or that the wifi connection drops. I would say that the computer freezes is more common than actual kernel attacks.


    I will try to re-install the OSX as you suggest, because when looking back I do think the crashes started at about the same time as when I made the upgrade to Mountain Lion (I did the upgrade in August)


    Will post the kernal attack next time it happens.


    Is there a log where I can see what happened before the computer froze?

  • freulv Level 1 (0 points)

    it's a normal mac keyboard directly connected to the usb-port

  • freulv Level 1 (0 points)

    I'm sorry guys. just discovered that the computer (less than a year old) was pre-installed with snow leopard. I found the original disks and I managed to get into the Apple Hardware Test. Did the full test, and according to the test there is nothing wrong with the hardware..

    Will try to re-install the OS X and see if it helps my original problem.


    Thanks for your help and support.