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New iMac 27inch screen flickering/tearing/shutoff

453198 Views 4,486 Replies Latest reply: Feb 9, 2010 6:59 AM by Brett L RSS
  • pors Calculating status...
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    Nov 29, 2009 11:03 AM (in response to Egrava)
    Egrava wrote:
    Thoughts?


    I think these are thoughts any of us has. And nobody has an answer to this.
    At least you should contact Apple support in order to have the problem reported. If you decide to wait if there will come a software or firmware solution you at least have the problem reported and can refer to it when it comes out that this is a hardware problem.
    iMac 27 i5, Mac OS X (10.6.2)
  • Warren Beasley Calculating status...
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    Nov 29, 2009 11:36 AM (in response to miscbeep)
    Hello MiscBeep,

    That is very disconcerting news regarding the ATI Radeon 4850 graphics card.

    If the 4850 truly has a known history of being noisy and running hot, I find it hard to believe that Apple would make it their GPU of choice for the new iMacs.

    Unless I am mistaken, isn't this the first Mac that actually uses the 4850?

    I thought that the Mac Pro might use the 4850 as well, but it has the Nvidia GeForce GT 120. Isn't this card -- the GT 120 -- older and slower than the 4850? ...although I have read that the GT 120 is better for game players.

    In fact, I wonder why Apple chose the 4850 when the 4870 and 5850 are already out. To keep the price of the iMacs down perhaps?
    733 MHz G4 Mini-Tower 17" Apple Display 400 MHz G4 Mini-Tower 17" Apple Display, Mac OS X (10.4.11), (1) Iomega 1 TB eGo USB Drive / (1) Pioneer 111D External DVD Burner
  • Warren Beasley Level 1 Level 1 (0 points)
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    Nov 29, 2009 11:43 AM (in response to Egrava)
    Egrava wrote:
    One more thought....

    If this is indeed a problem only experienced by a small percentage of shipped units then I wonder what are the odds that some people get 2 or 3 bad units in a roll. This makes me believe that the issue is much more prevalent then some speculate.


    That is a very interesting observation, Egrava, and I would have to say that I agree with you. It just doesn't make any logical sense that if only a minority of Mac users are receiving the defective iMacs -- as some here would like to believe -- that the very same people would also receive one -- or even two -- defective replacements. That seems very odd. As you said, the only rational conclusion is that the problem is much bigger, which would also help to explain why Apple is being so mute about it.

    I hope that we are wrong about this, but it certainly doesn't seem that way in light of your observation, does it?
    733 MHz G4 Mini-Tower 17" Apple Display 400 MHz G4 Mini-Tower 17" Apple Display, Mac OS X (10.4.11), (1) Iomega 1 TB eGo USB Drive / (1) Pioneer 111D External DVD Burner
  • wty Calculating status...
    how to tell which week my 27" i7 imac was built?
    the symptom repeated again this morning, going to call apple monday, or bring in to apple store.
    27" i7 imac, Mac OS X (10.6.2)
  • seventron Calculating status...
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    Nov 29, 2009 12:19 PM (in response to MarkyJ)
    believe me, i have been watching it like a hawk. then again, i have already decided to return it to best buy as i have ordered an i7 machine instead. i only have the base model. they are saying my order should ship around 12/11 i am having faith it won't have any issues after the way this thread has spread like wildfire. i will let everyone know. cheers!

    again, i will say i am still in shock apple hasn't formally acknowledged these issues...i mean come on!!!

    Message was edited by: seventron
    iMac 27", Mac OS X (10.6.2)
  • Thrice06 Calculating status...
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    Nov 29, 2009 12:34 PM (in response to Egrava)
    I've been thinking the same thing Egrava, mind you my first replacement machine never flickered and was fine working order I only replaced it because I noticed a scratch on the inside of the glass. And the last one I opened in the store was suffering from different screen anomalies and dead pixels. So if you think of all the different problems customers are having screen flicker, yellowing, dead pixels, scratch's, dust behind glass, and the list goes on. That is a lot of iMac's affected, I had 3 defective units myself.
    2.66GHz Core i5 iMac - 1.5 Ghz PowerBook G4 - 8GB iPhone 3G - 80GB iPod Classic, Mac OS X (10.6.2)
  • Warren Beasley Level 1 Level 1 (0 points)
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    Nov 29, 2009 1:17 PM (in response to Thrice06)
    Hello again Thrice06.

    Can you -- or someone else here -- please explain in more detail what this yellowing or tinting is?

    Are you saying that the image itself has a yellow tint to it, or are you folks referring to the glass cover on the iMac turning yellow?

    I am very curious about this, because as a long-time tropical fish hobbyist, there have been times when I have used plexiglass as my aquarium covers instead of glass.

    One thing I can tell you about plexiglass, is that due to the heat of the bulbs, over time, it will warp, become more brittle, and turn very yellow. Plexiglass aquariums are also notorious for easily being scratched.

    Another poster here -- I can't remember who now -- mentioned that he thought that the glass cover on the iMacs might actually be some kind of plexiglass, because he was able to lift it about two inches from the aluminum frame on one corner, and it was very flexible. I would think that glass, no matter how thin, would not be able to do this.

    If the cover really is plexiglass, and not glass, I wonder what it will look like after several years of being exposed to all of that heat.
    733 MHz G4 Mini-Tower 17" Apple Display 400 MHz G4 Mini-Tower 17" Apple Display, Mac OS X (10.4.11), (1) Iomega 1 TB eGo USB Drive / (1) Pioneer 111D External DVD Burner
  • patrickescott Calculating status...
    Arrived Friday, have had it on since then. Ran Handbrake conversions, played WoW, etc. So far, no issues.
    MacBook Pro 2.53, Mac OS X (10.6.1)
  • miscbeep Level 1 Level 1 (0 points)
    Hi Warren,

    Well, I'm just sharing what I'm experiencing here with my computer, and as far as I've read on the local/and not only forums, everybody buys a cooler for it ( like I did ) because it gets very hot. It's just the way the graphic card is supposed to be working, sadly, high pressure on it makes artifacts and flickering problems appear, as I've mentioned in my last post.
    You can verify my statements, if you just search around the net for problems with this GPU.
    I'm thinking, the reason Apple are putting these VGA's on the new iMacs is as simple as contract sheets between them. I read the other day that they have some arguings with nVidia. Plus lately ATI have simply showed me I have to switch to nVidia, because of the problems and the money I've spent for this GPU to work properly. So, don't find it hard to believe. Not sure though if the ATIs in the iMacs are not the mobile versions.. as I think a bit they must be.

    Not completely sure, but I think this is the first iMac using 4850.
    The nVidia GT 120 model, is the renamed nVidia 9500GT. Of course, the 4850/4870 are much more powerful than the GT 120. I don't think the GT 120 is better for gaming purposes.
    About that last question, my guess is that Apple ( as we know ) aren't always putting the newest and the fastest components in their computers, plus the space in the iMac isn't that big and they'll probably have a problem putting newer components, price is a good guess too.
    MacMini, Mac OS X (10.6.2), 4GB RAM, 320GB HDD
  • Gary645 Calculating status...
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    Nov 29, 2009 2:08 PM (in response to miscbeep)
    I've been following this discussion and am waiting to purchase a new 27" iMac once I see these problems have gone away. In the mean time I'm perfectly satisfied with my 24" iMac. Regarding the video problems, the very first post mentioned the problems with the 4670 GPU so it seems this is not isolated just to the 4850.
    iMac G5 & MacBook Pro, Mac OS X (10.4.8)
  • mpat Level 1 Level 1 (15 points)
    Note that the GPU in the iMac is a Mobile Radeon 4850. The overheating problems I can find online are related to the desktop model - specifically, the VRMs. The name is the same, but it's a completely different chip, and the mobile version uses a fraction of the power the desktop model does (around 45W for the mobile, 110W for the desktop).

    That so many people get repeat failures is the most confusing aspect of this problem - I commented on that a few pages back as well. That it isn't very common I take from the fact that it isn't being widely reported outside these forums, and the Mac web is usually quick to report any problems like these. From recent sales figures (Apple's share of the US desktop market climbing rapidly), we know that the new iMacs are selling very well, so even a middling failure rate would mean thousands of unhappy customers. They would have been heard by now.

    The yellow tint can be a panel issue or some sort of overheating - a yellow spot can be a hotspot inside the case - but it is unlikely to be related to the GPU. The flickering and blacking out are almost certainly GPU-related. They can be secondary effects from a overheating problem - in normal usage, the GPU runs much hotter than the CPU does - but it doesn't seem likely, as most faults are reported when the machines are quite cool from just starting.
    iMac Core i7, 27"
  • Chris Hylton Calculating status...
    Currently Being Moderated
    Nov 29, 2009 2:45 PM (in response to mpat)
    I just purchased a new 27" iMac on Tuesday; flicker started Friday. Returned today to Apple Store where I bought it, and they replaced it without any flack.

    I showed them this thread, and the production weeks that have exhibited the issue. Mine was a week 46; I had them go into the back and get me a week 47.

    So far, so good..... I have to say that I am quite impressed with the Apple Store employees who handled this replacement without any issues.

    I've been a PC guy all my life; this switch didn't start off like it should have. . .
    27" Intel Core 2 Duo 3.06 GHz iMac, Mac OS X (10.6.2)
  • samt14 Calculating status...
    This all sounds very similar to the initial iMacs (with ATI 2600HD). A lot of them kept freezing until they came up with a software fix. I have the 27inch imac, haven't had a problem yet. You guys having the problem, see if it happens when u restart the computer, i.e. start the computer, do something graphic intensive (like running the screen saver), if not glitches, restart computer and try it again. See if there are glitches then, that's what i did to prove the 20inch imac had problems.
    Imac 27 inch, Macbook Pro Unibody, Mac OS X (10.6), 27inch 3GHz CPU, MBP2.53 Ghz, 4GB
  • Leisas4 Level 1 Level 1 (0 points)
    Currently Being Moderated
    Nov 29, 2009 4:49 PM (in response to samt14)
    Got my 27" I5 on Friday, announced DOA this morning Monday
    Mac OS X (10.6.2)
  • John Trussell Level 1 Level 1 (5 points)
    I just switched out my 27" Core i5 iMac today at my local apple store, and I couldn't be happier! This was my 2nd bad unit (first one had a strange vertical line of dead pixels in the middle of the screen), so I am on my third iMac. Looks like the third time was the charm! No screen flicker, no dead pixels, no bleeding backlight, and barely any yellowing. I have to REALLY force myself to see the yellowing effect at the very bottom of the screen. This is a 947 btw.
    27" iMac Core i5, 8GB, 1TB Caviar Black, 4850, Mac OS X (10.6.2)
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