Q: New iMac 27inch screen flickering/tearing/shutoff

Yes, the end users will always be the ultimate QC'ers.

The biggest problem is that there is no way to test these machines for this particular flaw. It is doubtful that any amount of quality control could catch it.

The problem is so random, and unpredictable at this point, that it would require setting up each machine as it came off of the line, running it for several days, maybe even weeks, before the problem showed up, and then, someone would have to be sitting there staring at the screen, on each machine to catch it.

It would seem to me that it is far more cost effective on Apple's part, to go ahead and ship the machines, then simply replace them when they show the defect. Round trip freight for a unit would be significantly cheaper than the millions in labor it would require otherwise, and those additional costs would be reflected in the price we pay.

Obviously, thousands were lucky enough to get a perfect machine the first time, i was not among that group, I am among the few hundred that got a finicky one. While I am frustrated with the problem, I have faith in Apple to resolve it in a short period of time.

I ordered my 27" i7 before Thanksgiving and it arrived around Dec 3rd. (W8949 batch) First issue I noticed was the dead pixel SMACK in the middle of the screen, accompanied by a fleck or scratch or something on a different layer than the pixel. 1-800 Apple Guy said they generally won't repair for a few dead pixels, but the presence of something else in there made him suggest I take it in to the store. The store genius agreed it's something, and ordered the parts (new panel, new glass) to make the repair. Nobody in the store knew the Online Store's replacement policy, so they felt treating it like a repair was the most expedient route.

That night, with the machine back home waiting for the parts to arrive at the store, I saw the dreaded flickering, and the blackouts, and a few times saw the Dock appear "wrapped" to the top of the screen for a few seconds before snapping back to the bottom of the screen. I called the Apple store again to see if they wanted to order additional parts -- like a video card. They sounded like they had never heard of the flickering issue, and that I should bring the machine in when the panel and glass arrive, and they'll further diagnose the flickering. Which of course means that it will NOT flicker when I'm back in the store -- problems never appear when the technician is watching.

Perhaps I'll point the geniuses to this thread for more info, if they don't believe the flickering is an issue... I do suspect that the number of machines with issues is relatively low to the total number produced, but my bigger fear is that if they don't know the source of the issue -- why are the parts failing -- then they can't know for sure that the ones that work now won't eventually fail, too. Annoying, to say the least.

Well I received an email from Apple today the my 27" i7 has shipped and should be delivered on Dec 16th. I have my fingers crossed that I'm one of the lucky ones.

Well so much for that. Woke up today and my replacement iMac is now flickering and blacking out. At this point, I really don't know if its worth giving Apple another chance to send me a working product. Really disappointing and very inconvenient as every day I without a machine is a day of work lost.

I'm one of the first to report the problem in this thread and I'm beginning to lose my patience.. I've been living with the problem for the past month or so waiting for Apple to officially acknowledge or fix the problem. I refuse to exchange my machine for another faulty one as i need to get work done and can't be bothered with reloading OSX, loading apps, trips to the store, standing on my head, doing the rain-dance, etc.. Unless they are going to pay me hourly, it's an insult! C'mon Apple, sort it the f*ck out already..

Message was edited by: jmczaja

I've had my quad, 27 inch machine for almost a month, and the flickering, blackout problem is so infrequent and intermittent, I am sure now that it is a GPU driver problem. If it was hardware related, the screen quality might be deteriorating and the frequency of these faults would probably increase. Complete component failure or electrical arcing would be an obvious physical sign. As it is, a quick reboot instantly corrects the problem for what seems like days, and even weeks. So, it is highly unlikely it is temperature related (i.e.hardware). Graphic intensity seems to have little effect on the flickering occurrence. Complete randomness. Of course, some experience more of this than others.

So, fingers crossed with the first betas of 10.6.3 being released this week. Hopefully, somewhere in the build is the firmware solution to what we have been experiencing. Past history of firmware updates have addressed this very issue of screen glitches. It should be just a matter of weeks now, and this headache will be history. Fingers crossed.

Some people have had their machines a good while now and report no issues...

If it was ONLY a driver (thus software) issue, why don't ALL 27" iMacs show it?

BTW it does seem to happen for machines with either of the Radeon cards. I don't think those reporting the issue on the 21.5" model have said if they were using the NVIDIA or Radeon card.

- Karen

The flickering might be fixed with a firmware update, but for those of us who have a yellow tinge in the lower half (or anywhere else), we're out of luck. This seems like a physical defect so waiting for a firmware fix won't do any good. This is such a pain.

By the way my i7 is from week 49 and I don't yet have blackouts but the screen 'blinks' every 10 minutes or so (looks like a very quick refresh) and I do have that ugly yellowish tinge at the bottom of the screen, very noticeable depending on what is being displayed on the screen. I for sure did not get the 'ultimate display' as Apple is saying.

Message was edited by: nicolasj

I really sympathize with all the people that have this lower band yellow-tinge effect on their screen. I wonder if this, also, is related to a gpu/driver problem.

For instance, the LED backlights are probably located around the edge, so back illumination is not going to be localized. Therefore, this discoloration is not LED sourced, but LCD sourced. It is almost as if the default, the way I have heard some describe the effect, is like a lower half, graduated mask on the warm side of color temperature. Very peculiar. I would find it hard to explain as a physical characteristic of the screen, unless the membrane layers under the screen glass were unevenly affected. Would this banding be visible as a reflection from the screen when the computer is off?

What I did with my iMac, straight out of the box, was calibrate the screen with a Spyder device.

Some observations: prior to this computer, I had a G5, and when that screen got calibrated, it went from a warmer color to one that looked colder (6500k).

Now, on the 27 inch iMac, I find the calibration goes from a colder white point shade to one that is warmer (6500k again).

There is no substitution for a properly calibrated screen.

This would be bizarre, but perhaps the experience of partially yellow-tinged screens is the result of some skewed white balance settings with the LCD sectors of the lower half of the screens. we can only hope that is GPU related, and subject to a firmware correction.

I think we are a vocal crowd discussing this glitch, or defect; consequently, I don't know if this "problem" is physical and, thus, isolated to only the machines affected, or if it is software related, and widely, indiscriminately universal in its effects. Because it appears to be a random and intermittent problem for the majority of people discussing it here, it might not have become such a problem that the rest of the public, that are now taking possession of these 27 inch machines, have noticed it, or have deemed it be a worthy problem that they feel the need to seek out forums like this, and thus comment. Maybe there is a bigger, silent constituency of 27 inch buyers that are similarly affected, but are not showing up on this forum but only on Apple customer care phone logs. Extrapolate what you will.

A little over a couple of months is a short time for a product launch. Apart from the machines that are DOA, most have a working machine; albeit, one that occasionally has sneezing fits of flickering and blackouts. Enough to give anyone a bad case of buyer's remorse and anxiety related to $$$££££€€€€ and warranties, pride, etc....

I'm pretty sure the flickering is a software thing now.

I have set up the lower right corner of the screen to put the display to sleep (in Expose settings), and every time the screen starts flickering I just move the mouse to that corner and back. This resets the screen flicker for some days!

I hope you're right, following your statement, that trully can be a software issue.
Really a strange way to fix this for a couple of days, but if you've tested it it's good to know. Anyways I still want to say that this GPU is a total crap. I still haven't bought this beautiful machine, but I really consider taking the lowest - end 27 inch, since I bet that the 4670 is slower than the 4850, but at least having less overheating issues ( if it has any at all ).

I have not heard of the 4850 having heating issues in the iMac. I have heard the desktop 4850 having overheating issues, but not the mobility 4850.

Update to my last post:

http://discussions.apple.com/message.jspa?messageID=10689477#10689477
http://discussions.apple.com/message.jspa?messageID=10687811#10687811

Replaced the video card today and the problem did not go away. This tells me it is not the video card itself (or it is all of the video cards) or Apple is shipping repurposed video cards that have not had the problem corrected.

I ordered the LCD and Display cable today and they will be here in the morning tomorrow. I will replace them and report back.

The only other things it could possible be is the inverter (I doubt), software possibly (but I have my reasons I don't believe that), powersupply (maybe a voltage regulation problem or something).

Also, the whole things has to come apart to swap the graphics card, so I took everything out and reseated everything back in. So it is not a loose cable or anything like that.

I now have over 7 video's on my canon camera now showing the flickers and black outs.
How am I going to wait until Jan 15
Yellow ting across whole bottom of the screen but larger in the bottom right, a dead pixel and screen blur dot. Apple has as well as my insurance lady have both said Jan 15 at earliest.
Has anyone been told they have to wait this long for a DOA replacement?