vertical yellow lines on display
screen have vertical yellow lines - also at times have yellow pixals or blue
screen have vertical yellow lines - also at times have yellow pixals or blue
I'm having the same problem. I can get it started in safe mode but as soon as I restart it freezes.
Take the iMac to an Apple store genius bar so the techs can test it. There have been a number of posts over the past year or more with the same issue, vertical lines, sometimes yellow, or pink, or blue or mixed colors. Usually turns out to be a bad graphics chip, which can be repaired by the Apple technicians.
I have an intel 27" iMac. I've had my display replaced for another problem. Now I too have a vertical blue line on my screen. The Apple store looked at the problem and said it could cost $500 - $600 approx to either replace the graphics card or the screen. Have to say i'm not impressed. Thought Macs were supposed to be bullet proof. Guess if there are enough problems like these and Apple won't fix them then a class-action will start. I'll wait for that before I shell out $600.
That seems to be a problem with the iMacs, on rare occasion a MacBook Pro exhibits the behavior. Unfortunately all of these machines now have the graphics chip or module soldered to the logic board. Skilled technicians can remove and replace the parts, and at least it is not at the cost of a new logic board.
Since we are all fellow users on here and not Apple employees we really cannot do much beyond give advice based on experience. I have an iMac from 2005 that still runs, an iMac Mid-2011 that is really great, and an MBP Early-2011 that is great. Although it doesn't help when it is you that has the problem, statistically the number of failures is extremely low. That means Apple does not issue a recall as they have done with a specific serial number series of iPhone 5 models - those have bad batteries.
But give Apple feedback, http://www.apple.com/feedback and contact AppleCare, http://www.apple.com/kb/HE57 to register the issue. It takes everyone with the issue to let them know so this gets elevated.
vertical yellow lines on display