2011 27" iMac issues after Mavericks

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Level 1

75 points

2011 27" iMac issues after Mavericks

As soon as the system updated to Mavericks I have 2 major issues.

Randomly I start getting flickering "blocks of pixles" all over the screen in random places.

Only corrects itself on reboot and then starts back up at random times (ie does not seem to be time based of dependent to what I have open at the time)

The second problem is the system just crashes. Sometimes it reboots itself sometimes it is just off.

When it restarts on its own I get a pop up stating something about it was due to a recent software install (yeah Mavericks) or a kernel panic.

I have all the latest firmware and EFI as far as I can tell from the download site.

I noticed that the build is 10.9.2 (13C64) which according the OX Mavericks updates stie is for a 21" iMac with a completely different video card.

Not sure if that is really a problem as I have no control over which Mavericks it downloaded and installed via the "Software update" button.

Any guidance / assistance would be awesome. I am almost afriad to use the system in fear it will crash without recovering.

2011 Mid year 27 iMac

2.7G i5

AMD Radeon 6770M 512M

OS X 10.9.2

Posted on Apr 11, 2014 7:48 PM

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Answer 1

Apr 11, 2014 8:00 PM in response to Grinch

Try a Safe Mode boot. That deletes system caches that may help especially after an upgrade.

Startup your Mac in Safe Mode

A Safe Mode boot takes much longer than a normal boot so be patient.

Once you are in Safe Mode, click Restart from the Apple () menu.

Then see if the pixel anomaly returns as well as system crashes.

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Answer 2

Grinch Author

Level 1

75 points

Apr 12, 2014 5:28 AM in response to Carolyn Samit

Thanks for the suggestion. I did that last night.

Woke up this morning to the flashing pixels all over my screen again.

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Answer 3

Apr 13, 2014 12:57 PM in response to Grinch

I have had the same problems with by mid 2011 27" iMac. Today I downloaded OS 10.9.2 combo and installed. Problems so far have not returned.

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Answer 4

Apr 13, 2014 1:00 PM in response to Grinch

Doesn't sound good.

If you can, run the Apple Hardware Test

If not, take your Mac in for service > Apple - Find Locations

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Answer 5

Grinch Author

Level 1

75 points

Apr 13, 2014 8:49 PM in response to Carolyn Samit

Thanks, I completely forgot about the AHT.

I ran both the quick and extended test several times.

All PASSED.

Really this issue did not occur until I updated to Mavericks last week.

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Answer 6

Apr 16, 2014 5:45 AM in response to Grinch

Ok, as I said earlier the reload of 10.9.2 solved the problems UNTIL I ran Parallels. Then same old issues of flashing pixels and crashes. Seems that the latest bulid of Parallels has a flaw as described in http://forum.parallels.com/showthread.php?301274-Random-Virtual-Memory-related-K ernal-Panic-on-v9-24229. I switched to Fusion and have been problem free for the last two days. Hopefully this is a permanent cure.

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Answer 7

Grinch Author

Level 1

75 points

Apr 16, 2014 3:26 PM in response to ken-jacobs

how did you reload 10.9.2? Installing 10.9.2 via the software update is what started this whole problem.

I do not have parallels on my machine.

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