Chosen Solution
Display has been flickering and dimming during startup for a while now, didn’t really bother me, until I upgraded the hard drive to an SSD. Then the display started to become pixelated. I have already connected the iMac to an external monitor and the problem does not transfer to the external monitor. Attached is a picture how it currently looks. Not sure if the picture shows the extent of how pixelated and oversaturated the colors look. Any help will be greatly appreciated thanks.
Hook it up to an external monitor to help isolate the problem. If the issue persists you will need to replace or reflow the GPU.
Hello Alex, I can almost guarantee it is not the SSD that is causing the issue. That should speed up the laptop if anything. Although, I did some research and found an answer to this question previously. Because I don’t intend or care to take credit for their knowledge, here is the post that was solved with a person having the same issue: Scramble/Pixelated then flickering screen.. Best of luck!
I have an late 2009 iMAC 27inch. Have similar issue with screen. I post it the image. Does anyone see this problem before? I ran hardware test showing 4hdd/11/40000000:sata(0,0). I am not sure if this hard drive code correlate with a screen problem. Any thoughts on this?
I also want to add that when I run the iMAC in safe mode, the screen looks fine.
