My 27" iMac has worked great until about a week or two ago. The screen on occasion flickers. It does one 'cycle' in which it lowers the gamma and then raises it again. While its doing this there isn't a change in voltage being cycled to the computer, and there isn't any process that I know of that is causing it. Anyone else have this problem?
Yes, mine too. And just very recently. It's 1 year + a few days old (and yes... no AppleCare of course !) The flickering is really very light and intermittent so much that when I saw it in the first times I wasn't sure if it came from the screen or just an "illusion" from my eyes moving from one bright white opened window to the darker background of this huge screen ! But no, it is definitely a screen flickering. I did notice though that "cycling" the light dimming when it happens, like making it brighter and immediately coming back to my usual setting, seems to stop the phenomenon to appear for a few hours. For now. Because of course my worry is... is something dying !? I also suspect (and actually well... hope !) it MIGHT be due to a power source problem, I mean bad electrical current from the wall plug with occasional highs or lows. For a long time I want to buy an UPS and know I should do it. If ever I do this I'll report if any change.
Mine is doing the same. It's almost a year old now. I do have apple care so I'm going to take it in soon and see what they say. There is no method to the madness, it happens randomly but its not something I like to see so I'll reply back whenever I take it in next week and let you know what they said.
ok, this is getting me annoyed...
My iMac just started doing this today... but it is only when I am scrolling with my mouse.
there is a very fast intermittent flicker right in the middle of the screen across the entire width.
this computer is ~ 5 months old.
The only thing i did recently (yesterday) was update itunes... could that have done it?
i am tired of taking my iMac in to the Apple store... it's a pain in the rear to take it in all the time.
I posted a similar issue a week ago.
27"Imac i7 occasional the screen shimmers/flickers slightly in the background. More noticable on a white backdrop or when i'm using safari.
I usually find closing down pages on the screen and re open them seems to sort it out.
Dont know whether its hardware or a software problem.
If someone takes theres in please keep us informed of the outcome.
My 27" iMac also started flickering, mostly on white pages. It's a very subtle shimmer, like the hertz is really low. I first noticed this within the last 7 days. It's pretty distracting.
