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Sound stuttering after Mountain Lion install

Dear community,


after having installed OSX Mountain Lion my sound startet stuttering whenever there is rapid movement on my screen.

This includes e.g. window movement, scrolling through image loaded websites or video playback (flash player, quicktime).

A restart didn't help. I'm using stereo output, not digital.


I have connected a second monitor but the problem persists after disconnecting it. Movement on the second monitor also causes the sound to stutter.

My GPU Diode temperature is at 85°C (there is some bug that keeps the GPU under load while a second monitor is connected AFAIK), but I guess it was the same under Snow Leopard.


In Snow Leopard the sound output was always perfect even under heavy load or heavy HDD I/O.


Any ideas?

iMac (27-inch Mid 2011), OS X Mountain Lion

Posted on Jul 28, 2012 5:48 AM

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Posted on Jul 28, 2012 3:22 PM

I am also having this issue as well.


I opened Activity Monitor and noticed that during the stuttering, coreaudiod jumps in CPU usage, often past 5%. I have also noticed graphics lag when this occurs if I'm doing something like watching full-screen video or gaming.


I'm currently experiencing this on mid 2011 iMac 27" as well as a 24" iMac 2009 model I use at work.

1,223 replies

Nov 24, 2012 11:03 AM in response to pepper_chico

Pepper, you just proved my point. It said you needed a new drive and apple diagnostics advised replacement. That sounds like its detecting bad blocks. If you need it spelled out then that's your own issue to decipher. Apple writes software for English speaking not technical people. If you are a computer person as many of us are, you learn to speak both languages with apple. I think you're the only one with a faulty drive.


In another suggestion, I read a suggestion this issue might also have a tie in with AirPlay. Since most of the affected computers have airplay capability, it has been suggested that the computer is getting confused between what it should display and the airplay feature. Even when the feature isn't being used. This could be a worthless guess, but it never hurts to throw it out there.

Nov 24, 2012 11:10 AM in response to BarrettF77

It never said I needed a new drive. I don't even remember what it pointed, and worse, after such repair (operating as a windows chkdisk routine after some brute shutdown, does that means hardware replacement?), it said: repair successful.


It just looks like a common filesystem repair routine. It's not my issue for sure, it's plain bad diagnostics.

Nov 24, 2012 11:38 AM in response to BarrettF77

I'd like also to point out that, once upgraded to Mountain Lion, my system was slow before indexing, pram resets and stuff. After that my system acquired a normal speed, with ocasional mouse/typing lag, but the really most outstanding issue was the sound stuttering. I was using the system almost normally, I just could not play any song in iTunes. This looked very weird.


As time passed by too much, the lags aggravated, and Apple Disk Utility didn't helped.


Stuttering showed up in ML only. In Lion I had only some slowness, but it could play music.

Sound stuttering after Mountain Lion install

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