Q: Blinking pixels on screen after Yosemite install

Have the same problem. It take over 1/4 fourth of application window. Has occurred in Safari, Firefox, App Store, and others...

MacBook Pro (15-inch, Early 2011)

2.3 GHz Intel Core i7

16 GB 1333 MHz DDR3

Intel HD Graphics 3000 512 MB

I have the same problem. The screen freezes sometimes and I have to restart the computer

iMac (27-inch, Mid 2010)

2.8 GHz Intel Core i5

ATI Radeon HD 5750 1024 MB

Since 10.9 upgrade, and now Yosemite, my mid-2011 iMac has pixels flashing on the desktop, regardless of any software open, such as iTunes, Photoshop, or other approved software on Apple.  This also freezes up the iMac.  I have emailed Support since OS 9 and nothing changing in a fix from Apple.   I erased the hard-drive after a major freeze that would not allow saving anything from the hard-drive and put on OS 7+ which worked fine.  I did not like OS 7 anymore so upgraded and now it is worse than before in Yosemite.

This computer was checked at an Apple store and has no structure issues.  I also checked it via other sources to confirm and their are no structural issues.  It is entirely 'OSX' in my not humble opinion.

I researched and find no fix available but others also having the same problem, seemingly since OS X 9.

I have never seen Apple continue to totally disregard an issue of an upgrade on any Mac computer before and I have been on Apple since its first computer.   I worked at McGraw-Hill Publishing and was involved with 'Byte' magazine and its interview with the then upcoming MacIntosh. 

My experience in this truly disappoints me with Apple on this issue.  I hate to purchase a new computer just because engineers are not responding to a real issue that is now worse with Yosemite.

I hate it when all of the 'wiseguys/gals' 'round here ignore a question. I have one posted myself that has gone unanswered for days......so, as to your problem -> After my Yosemite install I also had 'blinking pixels around the upper part of my screen. I reviewed some old answers and found something from kappy. I reset the PRAM. Restart your iMac, and immediately after the first chime, simultaneously hold down option-command-p-r until it chimes once more, then release. Then I reset the System Management Controller (SMC), which is simple-just turn off your computer, unplug the power cord for at least 15 seconds, replug and start. SO FAR (1 hour) no weird blinking pixels have appeared. I hope they don't return, but, so far, so good.

Good luck,

Fred

see the reply to this on the page....it worked for me! The best with yours!

Update on Pixel issue.  I read on line to UK MacWorld and in their article it was stated in 2013  that graphic cards are failing in certain models of mid 2011 iMacs and Apple replacing and I have the exact model of that article.  I called support on the evening of Oct 20 and have an appointment to take in the iMac. 

Interesting, in my searching I could find nothing in the US on this but from UK the issue is in their online Macworld.

I will update after my appointment as to the service.

well, after a 10 hour or so workday, I came home, and was cruising around on the Mac, and discovered that the blinking pixels had returned. BUT, in response to the above post by David Peterson8, I found this:

"There is a new GPU replacement program for mid  2011, 27 inch iMac models.

If your iMac serial numbers end with certain letters, your iMac maybe eligible for a no cost replacement GPU.

Contact either Apple directly at 1-800-MYAPPLE or contact your nearest Apple store and ask about this and make an apappointment at the Genius Bar to bring in your iMac if your iMac is eligible for the free GPU replacement.

http://www.macrumors.com/2013/08/16/apple-initiates-graphic-card-replacement-pro gram-for-mid-2011-27-inch-imac/

I'm gonna be calling them tomorrow to see if I fall into the privileged group.

Good luck with yours, PP.

Does it look like this?

Experiencing this issue on my Mid 2010 27" iMac.  Worked great before 10.10 GM upgrade.

10 sec video of it in action, it can get pretty bad and even freeze the machine.

Doesn't seem to happen in Safe Boot, but not sure if that means software or hardware issue yet.

Safe Boot loads more basic Graphics drivers than the full blown OS, which is why you may not be seeing this when booted to Safe Boot.

patscalan, I see your image above is a photo (as opposed to a screen shot), what happens if you take a screen shot when the issue is occurring?  Is the distortion visible in the screen shots too?

Its hard to tell from the video if the issue is LCD or GPU based, however the patterned nature of the issue could suggest this is a GPU (Graphics Card) related issue and not a software issue.

Let us know how you go.

Screenshots don't seem to capture it.  If I drag the cursor over the screen in an attempt to capture it, the border of the box crosses over the discoloration and it goes away.  Hope that explanation makes sense.

I did a 10.10 reinstall and same issue.  Have a Genius appt. on Thursday, hope they can help resolve the issue.

Hm... So by moving past it with the box edges, the screen draws correctly? Have you tried a screen capture that doesn't require you drawing a box (Shift-Command-3)?