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

Does anyone know or can anyone point out a link to statistics on
how many new iMacs suffer from this flickering problem?

mr da wrote:
Does anyone know or can anyone point out a link to statistics on
how many new iMacs suffer from this flickering problem?

http://imac.squeaked.com/ collects reports from this forum & perhaps elsewhere on the 'net. Great site. No one knows how many cases there are overall, but all evidence points to the problem being somewhat widespread (e.g. many folks reporting getting multiple bad replacement machines (statistically unlikely if % of bad machines is small), plus most of the "good" units seen in stores are week 40-41 models that have had very few bad reports (i.e. not many 42 week+ units still on display in stores)).

I see some of you saying that you don't think heat is an issue because it happens cold.

Think about some of the issues that plagued the first gen Xbox 360. Part of their problem was the type of solder used during the manufacturing process. The connection between the GPU and PCB board when heated to a certain temperature compromised those connections forever. So later on (some reports after one use) the problem existed hot or cold because the solder/GPU/PCB had a bad connection.

Some of initial work arounds included wrapping it in a towel and letting it heat up to re-melt the solder (eek!). It worked but was only a temporary fix until the unit heated up again and those connections could not pass the proper voltages anymore.

If any of your units have ever heated to a certain temperature it is possible that they could have been compromised before Apple released the firmware that increased the fan speed. I remember seeing an earlier post where someone made reference to Apple telling them the firmware fix would not fix the issue if your unit was already having the issue. This reminded me of the Xbox issues. Anyway, just food for thought.

Good comment on the sensor distribution. Happily I live in Minnesota, and at this time of year cooling is quite simple. I'll just leave the window behind my iMac open a bit. The soothing air flow should keep the heat demons asleep while we wait for Apple to fix this. (Note Apple often doesn't admit to a problem or acknowledges a fix even for fairly severe quality and hardware issues, so we have to keep watching and talking.)

Thought I'd add my experiences...

My 27" i7 did not exhibit the problem prior to the patch at all. It ran fine even after many hours of programming, document writing, or gaming.

After/since the firmware patch, it's been displaying flickering, tearing and shutoff/blackout pretty regularly. One of the above every couple of minutes at best, once every 10-15s at worst. However, this only occurs in OS X. I dual boot Windows 7, and have yet to see it once while running Windows (usually playing games).

I have bluetooth and wifi turned off, and the original hard drive and optical drive have been replaced with SSDs.

In my case, heat doesn't seem to be a factor. It happens immediately after power on after having been off all night, and temps via iStat are indeed low. It happens after prolonged use as well, but temps are still reasonable. I've been monitoring it for a couple of days to see if heat is a factor in my case, and my data suggests it is not for me. The fact that it doesn't exhibit any problems when running Windows 7 while playing games, which get the machine running much hotter than anything I do in OS X, also suggests heat is not the cause in my case at least.

To experiment, I tried running several benchmark apps concurrently, while encoding video and several mp3's in OS X in an effort to get it hot, and the problem continued to occur even after ~30min of stress testing. In OS X, for me, it happens at all temp levels, and I can't seem to deterministically inflict the behavior. i.e. hotter or colder doesn't affect the duration between incidents, they're always seemingly random, and they've been continually occurring since the patch. Maxing out all of the fans with smcFanControl didn't make any difference either, whether under massive load, or completely idle.

The only other item of note, is that watching a DVD, or any flash video tends to make the behavior more erratic. If I pull up a show on fox.com or syfy.com for example, it does seem to occur more frequently, and is the blackout problem in those cases.

Watching the exact same show on Windows did not have any problems whatsoever, whereas I had 4 blackouts and a couple of flickers in the first 90s on OS X...

I have a Week 41 machine and have yet to have any problems whatsoever other than a drain on batteries which is covered elsewhere. I will not do the "Firmwear patch" as I have noted that others that had no problems with their iMac and did it started the problem up. I will post here when and if I have any of these problems. Maybe I am one of the lucky ones? Sorry that we are not all that lucky.

Peter, how long did you have your i7 before applying the firmware update?

When I received my current i7 on 12/23, I literally took it out of the box, turned it on, reinstalled OS X from disc, and applied the firmware update. I haven't had any flickering yet (knock on wood), but I know that's not really indicative of anything at this point. The i7 that this computer replaced (that one had a baaad yellow tinge problem) never flickered once in the three weeks that I owned it.

Update from my side: Apparently on my case I logged a few weeks ago on mine with Apple support, I called back in and the rep said that engineering noted on the case that the known parts to fix it were attached to the ticket. I've contacted my local Apple Auth Repair Center (closest one as there is no Apple Stores within 2 hours of me) and hopefully they are ordering the parts for the repair. At this point all the rep would mention was that it is an LCD replacement AND additional parts. My guess: LCD, connector cable and the power unit for the thing. I'll let you know once I get more info.

thxdude
These repairs match what AppleCare have told me to get fixed - a new screen and LCD cable (no mention of a power supply though). Been waiting for the Apple Repair Centre nearest to me to get the screen for the last three weeks. Got an email today saying it's going to be another week. I'll report back with the results once they're fitted although I'm not convinced this is the solution - feels a bit like a shot in the dark in the conversations I've had with the techie.

I've got a 27" i7 iMac made in Shanghai week 50. It was delivered to me on 12/23, and it had the flicker/black screen problem the moment I started using it (didn't notice during data transfer from my old iMac's Time Machine backup). It had the firmware update already installed.

The next day the flicker frequency slowed down, and for the next few days I didn't see any flicker. Today the flicker and black screen came back with a vengeance. I've basically done the same thing for the last 5 days, so I don't think it's any usage pattern.

I called Apple support, and they want me to send it back to engineering so they can look at it. I said yes because I want this problem solved. They're going to email me FedEx labels to send it, and expedite building a new machine.

Well, back to the 24" 2.4 iMac. At least I haven't wiped it yet!

Hello to All,
I have been watching this topic with some concern.... closely following the nuances, opinions and perspectives - as has been provided by all the affected Users and other interested parties.

I do so because I will be receiving my first 27" iMac (C2D) next week (ex singapore factory).... this being a replacement machine (supplied under Applecare Warranty) for my 18 month old (and much loved) 24" iMac (C2D) which endured many component failures & replacements; Optical Drive (x2) HDD FAN, HDD and finally the Logic Board & Video Card. (Note: all to no avail... in fixing/resolving a persistant "Kernel Panic")

Of all the scenarios (and suspicions) presented in this topic... I was wondering just how many of the affected 27" iMacs were subjected to a data transfer - from previous machines, as opposed to doing a clean install of a User Data & Applications onto their newer 27" iMac ?

With regard to the 27" iMac.....Could it be that those machines being affected - is due to installing something (unnoticed) from an earlier Machine or OS - that is incompatible with the new Machine, its components or OS ?

Can anyone with an affected 27" Machine.... 'state or confirm' this problem existed BEFORE they installed anything additional - to then modify what actually arrived in the Box...?

I have reservations about Snow Leopard... as I believe it had much to do with the demise of my 24" iMac.

Just my 2 cents...?

I migrated from an older iMac and so far, knock on plastic, I don't have any of the problems. I've only had my week 51 machine up and running since the 24th, but as of the moment:

* no flickering screen
* no screen blackouts
* no yellow tinge. I think I might have a light strip of "yellow"across the bottom 1/8"or 1/16" of an inch, maybe
* no noisy hard drive

Now, I realize all this can change at any moment, but...so far...we're doing ok.

Hi hkrause,
Thanks for that info.... can you tell us which Model of iMac and importantly.... What version of Mac OSX
was current - when you migrated everything to the new 27" iMac ?

I migrated from the current version of OSX... 10.6.2. I bought that version of the OS when it came out... a multiple (5) machine version. My previous iMac was about a year old, a 3.06 Ghz machine with no problems. I sold that machine and used the proceeds to buy the I7 unit.

BTW, when I got my new I7, the "fix" had already been installed.

My theory is that screen problems are the result of sloppy or incorrect assembly on some machines, couple with a total lack of QC checking once the machines are assembled.

I'm leaning towards the "sloppy assembly" theory.

NULCGI, check out http://imac.squeaked.com/ for a ton of user supplied data on the new iMacs.