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Jan Sampermans Level 1 Level 1
I have been experiencing some problems with the all new iMac 27inch display.
At non-fixed intervals i will get one of the following:

Screen distortion/flicker somewhere random in the screen (feels like it is more in the lower part) that looks like a horizontal bar of about 2-3inches just popping in and out of the screen.

Screen will go completely black for a second and then come back on. Sometimes 2-3 times in a row.

Somebody else already made some video-clips about these problems, I am experiencing exactly the same behaviour.

Just to not that in the course of writing this post my screen has flickered 13 times and has gone black 2 times.

iMac 27inch 3Ghz 4GB 1TB ATI 4670, Mac OS X (10.6.1)
  • sshomza Level 1 Level 1
    Hey guys,

    Just been following this on macrumours.

    Only suggestion I have to see if it might be the panel or the GPU (could be something else), is for someone that is experiencing this and has access to a PC/mac, could you run the 27" as a display. I know only some of you will have adapter for this, but this might be a good way to work out if it is the GPU or panel that is having issues. In theory if you run the 27" as a display only it will not use the imac GPU.

  • robotkiller Level 1 Level 1
    I had a flickering problem with my 27" as well.

    It was impossible to reproduce. I could work for hours on the computer and then suddenly it would flicker randomly with a band of horizontal static bars about 3 inches thick momentarily or, alternatively, it would black out for a fraction of a second. This could happen up to once every 5-10min.

    I was able to return the computer to the Apple Store, who were reasonable enough to waive the restocking fee.

    I suspect that this is a hardware issue. I almost hope that it is - that way it will be more common and fixed sooner.
  • capricia Level 1 Level 1
    I think there is anybody with the same problem. Since this morning my display of my 27" iMac show the menubar in the middle of the display and above there are a lot of vertical lines in multi colors. Now I think this one is not a problem with the driver, I hoped this first, I think there is a problem with the graphic chip.

    First it was a sporadic flickering like your iMac but now the iMac - the display - goes more and more defect.

    At the moment I take a backup of my HD, well - its better to bring the iMac back.
  • UCLAMacConvert Level 1 Level 1
    Saw this very thing (flickering/glitching display) on one 27" iMac in an Apple Store in West Los Angeles. The other 27" iMacs were fine, but one out of five in the store had the problem.

    I was set on ordering the i7 CTO 27" iMac but now am going to hold off until they resolve this...
  • jmczaja Level 1 Level 1
    Got a new 27" iMac yesterday and had no problems whatsoever all night.. After waking the iMac from sleep I began to see this flickering problem. The machine was not hot whatsoever so I dont think the issue is heat related. One thing I did was manually put the machine into sleep mode and waking it up again. Since doing so, I havent seen the problem. Something is telling me that this is a software issue. I wish apple would confirm this before the 14 day return period is up.

  • newanalog Level 1 Level 1
    Apple is swapping out my 27" as well. Hopefully there was just a glitch in one of the "batches" and they've fixed it by now.
  • artka Level 1 Level 1
    Just bought the 27" yesterday and noticed the flickering while Firewire transfering my older 20" imac over to the new one. I thought it may have been the LED adjusting or something. The iMAc was cold, first time turned on.

    I let it sleep overnight, and once again, while cold, I turned it on and the flickering and menu bar on the top portion of the screen is happening. It does this for roughly five minutes then it goes to normal? I have no idea whats wrong and its annoying and scary... software or hardware? I'll wait a few days before taking it in, but this needs a fix ASAP. I can imagine how its going to upset many.
  • artka Level 1 Level 1
    Forgot to add: I tried taking a screenshot while it was in the middle of this process, and the screenshot shows a normal desktop, as if nothing changed (the horizintal static was not on it). I'm not sure how the system takes screens, but I'm not liking the fact that the screenshot was normal... this points to an unfortunate hardware issue. I hope I am wrong.
  • pschaf Level 1 Level 1
    Just started getting the same issue... wow. Google search pulled up this forum. Seems to be getting worse. Quick flicker of bar at the lower half of the screen. No real way to reproduce. Have tried restarting and also sleep.

    This was my first Mac, purchased a few days ago. Maybe I should sign up for AppleCare now...
  • Macattack515 Level 1 Level 1
    I received my 27" iMac three days ago and ever since i got it out of the box and turned it on it has done the same as the video shows.

    Last night i watched a 30 min programme on BBC iPlayer and the 2-3 inch white lines kept popping up every few seconds horizontally across the screen. The screen also went black momenterally on 6 occasions.

    I cannot believe after three days that this problem is so bad. I spome with Apple this morning on the Apple Care line and they told me to:
    1. Shut down and take out power cord for 20 secs then turn back on.
    2. Shut Down and then hold down "D" when turning back on which performed a hardware test...
    Both had no effect.

    Luckilly i am still within the 14 days of recieving my iMac and they are sending out a replacement but i am worried that this machine will have the same problems...

    Is anyone happy with theres and is anyone not experiencing this problem... There seems to be a big issue here???
  • artka Level 1 Level 1

    I'd appreciate a follow up once you get the replacement. Hopefully it wont have the same problem, but please let us know what comes of it.

  • billybuds Level 1 Level 1
    Same problem here, the momentary black screen and the flickering. Seems to be very sporadic, won't happen for a few hours and then seems to happen every 20 seconds or so. Also the computer sometimes won't wake from sleep, not sure if its related, but if I recall correctly the first time it happened was after it was difficult waking it from sleep.

    Spoke to apple today, ran me through the regular steps (power cord out for 20 secs, etc) and was fine for a few hours but has now started again. This is my first desktop mac, and I'm still within my 14 day 'grace' period......should I be tempted by a windows 7 machine...?
  • Gable31 Level 1 Level 1
    Just received my iMac 27" from Shanghai. Screen has flickering and going black. Have called Apple tech support to begin replacement process. Makes me question the life span of the LED screen technology. Is this going to be my screen experience 1 day after the AppleCare runs out? I hope Apple addresses quickly.
  • Gable31 Level 1 Level 1
    Should I even bothering setting-up this iMac ad downloading music and photos or will I need to do this again?
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