7 Replies Latest reply: Jun 28, 2013 1:44 AM by Fidget91
Fidget91 Level 1 Level 1 (0 points)


I'm writing as I'm experiencing a weird issue with my iMac I've never run into before.

I'm on a 27" iMac i7 3,4GHz with 16GB RAM and a AMD Radeon 6970M 1GB GPU


My iMac started crashing with glitchy, vertical and horizontal lines. When it does these crashes whatever audio has been playing is "looped" in a very typical crash'y behaviour. I've been following different topics like a madman and I'm pretty sure it has to do with the GPU temperature that sometimes reach 90-95 degrees celcius (which is close to 203 fahrenheit). Opening the windows and using SMCFanControl to keep the fans spinning a bit seems to help the issue, but it's not really a durable solution to have my computer sounding like a vacuum cleaner just to be able to use it.


For the record I do no graphics intensive tasks and do only music production on my computer.
I've never experienced these problems in Snow Leopard, but then again I haven't had more than a few Kernel Panics in Lion - the computer does feel noticeably hotter in Lion though. The GPU crashing problem is relatively new, and I'm considering dust to be an option (even though my house is relatively dust free) - but I'm not the biggest fan of (and techsavvy enough to) cranking my screen open to vacuum clean its guts.


I attached a picture taken with my cell of how the screen looks during these crashes.


I'm dying to find out what this could be. Keep in mind this started about 5 days ago, and have never been an issue before. I haven't updated any software prior to the symptoms except for Logic Pro, but it would seem weird to me that an audio application is causing GPU overheating, and besides the GPU is still very hot when I'm not using Logic.


Hoping for a solution!

iMac, Mac OS X (10.6.7), Intel i7 3,4 Quad, 16 gb ram
  • Rudegar Level 7 Level 7 (23,640 points)

    my guess would be a fan in the imac have broken down and the lack of cooling it provided is the cause of your problems if so it would require repair

  • clay58 Level 1 Level 1 (35 points)

    I looked at the temperture of my GPU and it is running at 119 degrees fahrenheit which is pretty normal. The CPU is running at 104 degrees fahrenheit You definately have a cooling problem. Have you tried vacumming the air vents out both on the bottom of the screen and on the top rear of the screen. If that doesn't help then you may have a cooling fan that has failed. The CPU fan on my 2009  iMac running Mountian Lion is turning at 1150 rpms. Install iStat Pro that will telll you if the fan is actually running or not.


  • Fidget91 Level 1 Level 1 (0 points)

    How would i find out if it's a vent that broke down? Any way to find out without mauling/disassembling the computer?

  • clay58 Level 1 Level 1 (35 points)

    All you can do short of taking your Imac apart is to turn it off and vacuum the inlet on the bottom of the screen very throughly with a strong vacuum cleaner. Also vacuum the outlet on the top. If you install iStat Pro it will tell you if the fan is running. If the fan is not running it must be replaced. There are videos on Youtube showing you how to take an iMac apart if you feel qualificed to tackle it. It may just be it is very dirty. Good luck.

  • WZZZ Level 6 Level 6 (12,775 points)

    In addition to getting iStat Pro, which will allow you to see temps and fan speeds (if a fan isn't workng, you'll be able to see that), run the hardware test in extended mode. It may be the graphics card is going south.




    Also, boot into Safe Mode, which will disable quartz extreme graphics. If the screen artifacts stop in Safe Mode, then it's very likely the GPU.


    Hold Shift down at the startup chime. Expect it to take much longer to boot than usual


    Also, there is an intake grille for the cooling situated just behind the stand. Make sure that's clear and clean.

  • Delsorbo Level 1 Level 1 (0 points)

    Have you had any luck with a solution? I am having the exact same issue. Going to run some test tomorrow to check on the fans and maybe do an extended hardware test on the GPU. I do have an appointment with the genius bar on the weekend, but would like to avoid lugging this thing around.

  • Fidget91 Level 1 Level 1 (0 points)

    Hi Delsorbo,


    I actually did fix this! You often forget about the support topic once the problem is solved :-)


    Even tho hardware test showed nothing wrong with my gfx card and neither did the repair guys test, i was indeed right in my assumptions. They couldnt recreate the problem or make it happen but my filmin and taking pictures was enough for them to REPLACE THE VIDEO CARD.


    After having it replaces i've had zero problems and its been smooth sailing ever since. Keep in mind this is even though they didnt diagnose any problems with the gfx card and couldnt recreate the problem, so arm yourself with some evidence before headin there :)


    Nothing else has been done to my comp, no harddrive replacement or anything - but with a new gfx card im now on my 2nd month of no issues whereas previously it'd happen 6-7 times daily. Proof enough for me.


    Wish u the best