Solve Your Mac Freezing/Hanging In Mountain Lion 5


Solve Your Mac Freezing/Hanging In Mountain Lion


Today’s post is going to be a bit specific, however it helped me solved a long running problem where you Mac would freeze / hang after waking up from sleep, freezing during normal use and it randomly freezing through out the day. It was a real pain, however, I managed to solve the problem due to the switching of the graphics card in my MacBook Pro. Although this may not solve everyones random freezing problem, it may help those in specific circumstances where there MacBook would hang for no reason.

The Hanging Issue

Your Mac may hang for a variety of issues, some may be hardware related such as a corrupt hard drive, or RAM. Others may be software related such as an unstable kernel release or a dodgy app interrupting everything. My solution was down to the two graphics cards found in my MacBook Pro. In everyday use the low wattage internal graphics card was used, then as the power needed turning up the bigger better dedicated graphics card kicked in. This means that I get good battery life when I am surfing the web and a good amount of power when I am playing games.

At some point there needs to be a switch. Your Mac is pretty good at doing this, however I found when I upgraded to Mountain Lion the freezing issue appeared. It would randomly hang when I woke from sleep, or when I was surfing the web. It happened randomly throughout the day.

The problem originated when I was looking through the console. Located in Applications > Utilities. Under ‘All Messages’ and system.log the following would appear:

kernel[0]: AMDCaicosGraphicsAccelerator: ** Device in slot: SLOT--1 **
kernel[0]: ** GPU Debug Info Start **
kernel[0]: 0x00006760
kernel[0]: ** GPU Debug Info End **
kernel[0]: GPU hang: Not Implemented
kernel[0]: Trying restart GPU ...[1] ( Throttling respawn: Will start in 4 seconds

This would appear at the same time of the freeze. The mouse would not move, no keyboard entries could be made, the clock would not update. A full system freeze. The only solution was a hard restart.

The Solution

The solution to this problem was rather simple. Turn off graphics switching, then turn it back on at a late date. This disables the graphics switching option, causing the hang not to occur. I then later turned it back on with no ill effects.

To turn off graphics switching open System Preferences and click on Energy Saver. At the top of the preference you will notice an option that controls the graphics switching. Turn this off.

Turning off graphics switching stopped the graphics freezing issue.

Immediately the graphics hang option stopped.

When you are satisfied that that the graphics switching and hanging issues has stopped you can turn the graphics switching back on. I have had a happy non-freezing Mac for many days.

It is only a simple change, switching something off and on again. But it solves a deep problem. It may not work for you, but it may be a solution for others. I had graphics switching turned off for a week and when I turned it back on I had no ill effects.

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5 Responses to “Solve Your Mac Freezing/Hanging In Mountain Lion”

  1. 1

    Hi. I was having this same issue one day and I did a hard power off/on and also did narrow it down to the graphics card. The issue came up to me when I turned the MacBook Pro off and asked it to “save” my programs in the state they were in, at the time my Mac was hooked up to an external monitor. When I turned it back on it was actually disconnected from the monitor, and I figured that was causing issues.

    But it’s nice to see your work in solving the actual problem at hand and how you did it. Now I will know what to do if it ever happens again in the future. Thanks!

    Comment By Usama Ahmad on November 12th, at 7:52 pm

  2. 2

    For your problem there is one other solution. Never lat your machine sleep. I don’t. I let the screen go black but the HD is still spinning and my apps still running. I use NoSleep and Caffeine.

    The solution I’m looking for is with Airport. It started with the installation of M.L. If I move from one router(Airport Extreme) to another and then back to Airport Extreme, Airport does’nt crash but does’nt load properly and hangs and I have to do a Hard Restart. It can search forever for the Extreme and never really find it even though when left clicking in the icon it shows it found it. It probably something very simple that is hanging either Airport or the router but I have’nt been able to track it down as of yet since installing M.L.. The Apple use groups have’nt been any help either.

    Comment By Cold Waters Run Deep on November 12th, at 8:22 pm

  3. 3

    I seem to have the same graphics card problem causing hangs and a need for a hard restart, at least once a day, but on a desktop, so I don’t get the same system preferences screen because there is no battery involved. And I’m not switching routers. Any other ideas?

    Comment By Jane Garthson on December 22nd, at 4:53 pm

  4. 4

    I solved my hanging problem by making the SMC firmware update.

    Comment By Karl on December 31st, at 9:30 pm

  5. 5

    Comment By Karl on December 31st, at 9:31 pm