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

Did anybody noticed, if it is flickering of the back light source, or a blackout of the LCD panel (or both)?

Tom B.

I am happy to report that my 2-week old 27" i5 is still flawless - I did the firmware update and I am running a graphics program 24/7 - waiting for a problem.

It does make me wonder - how many 27" iMacs have been delivered - and how many have a problem? How rare is it?

Will mine eventually crash - or am I just lucky?

Could it be the pure and wholesome nature of the rural midwest the allows my computer to work? Do only inner city iMacs crash? Bad vibes and static on the wires? Air pollution???

I think you're suggesting that there's a congenital frailty that interacts with environment to produce varying symptoms. Rather like humans.

I buy that. I also think there's a range of "genetic" predispositions to flicker. Some machines sound like they will flicker anywhere, or even have more severe issues.

My machine flickered 1-2 times at the original spot. So it was low flicker to begin with. I moved it to a different room in the same house -- no more flicker over 1 week. I haven't bothered with the firmware update.

Main changes: distance to 802.11n 5Ghz Time Machine, wall outlet. Temperature about the same.

I think it will take some time to work this one fully.

Joe, I had 25 programs loaded and many actively running graphics tasks without a problem after having my first flickers corrected by a PRAM reset. I thought I was home free. Later I only had a couple of minor apps running and I had that problem where the Menu bar is about 1/4 the way down the screen and the dock is at the top of the screen!

So I'm not out of the water yet. Redid the PRAM reset and no problems yet but I no longer have any confidence the fix works or the PRAM reset does the trick. I could have blown my nose and it probably would not have flickered for a few hours.

THe black screen seems very black, but mine only last a second so one's eye does not have time to adjust to the change in light to see if it's the LCD or LED or both, but my guess is both as I don't recall noticing any 'glow' through the black screen.

Well mine flickered and blacked out today after the firmware update as well, surprise surprise. Guess I am calling apple tomorrow about my machine and seeing what I can get done.

UPDATE:
Apple corporate customer relations called me today and said I would not be receiving the upgrades on my replacement machine followed by an apology about the miscommunication? The machine is scheduled to ship January 2nd. They are not reimbursing me for my time lugging the machine through the mall, talking to over 6 representatives, and the time I'm spending without the machine. I'm scheduled to make my first payment before I even get a functioning machine? What should I do?

If the problem was environmental, it would imply that everyone with the problem had there machine setup in the same environmental conditions. Very unlikely, if not impossible.
Many people, my self included have reported that the problem was gone after restarting or sleep/ wake cycle .
So changing where the computer is pluged in will most likely produce the same result. Problem is, it seems to be only a temporary fix for most of us since the problems return after a week or two , sometimes longer.
If the cause was electrical, because of say a batch of bad psu, that would have been easy for Apple to identify.

Are people doing a PRAM/NVRAM reset after the firmware update? If so, does this have any effect on the success of the update or is it too random to tell?

I have very infrequent flicker events that are fixed by a display sleep/wake. I'm reluctant to apply the update in case it makes things worse which seems to be what some people experience.

To be honest I haven't done it to mine and that is only because I am not at home now and am out of town on business. The wife reported the blackout to me.

I do recommend though that everyone after doing the firmware update try both a pram and a nvram reset. I will try when I get home in the next couple of days.

As I suggested a few pages back, it may be that the data is still corrupted in the video memory and that is why the firmware is not appearing to fix it. Of course it may also be that the firmware is complete bull

If it need the pram reset after, I would have assumed apple would have mentioned that, but who knows at this point.

CliffBell87 wrote:
UPDATE:
Apple corporate customer relations called me today and said I would not be receiving the upgrades on my replacement machine followed by an apology about the miscommunication? The machine is scheduled to ship January 2nd. They are not reimbursing me for my time lugging the machine through the mall, talking to over 6 representatives, and the time I'm spending without the machine. I'm scheduled to make my first payment before I even get a functioning machine? What should I do?

Man, that's friggin' B.S. I don't think the upgrades they offered you were really called for, but since they made the offer, they need to follow through. Having said that, I'm not sure really what there is you can do. You can threaten to cancel your order, but be prepared to do just that if they call your bluff. If you really want the iMac, you probably should just swallow your pride and take what they're dishing out. If, on the other hand, you're so upset about the way you've been treated that you don't want to give them another shot, then by all means, threaten to cancel unless they follow through with their initial offer.

Does the flickering occur when you are running Linux natively?

Sonic, what exactly is the difference between pram and nvram reset? Aren't they both done with that four-key-grip at one time?

Are there any other resets one could or should do (I remember the main board of my old iMac G5 having a sort of knob one had to press while the machine was open and disconnected). Wouldn't' want to open my new i7 though...

Thanks for a hint!

SMC reset http://support.apple.com/kb/HT3964
PRAM reset http://support.apple.com/kb/HT1379

Hi everybody,

OK it's really weird!
I couldn't believed that the power could be the problem but here is what happened.

I did have a flickering/black screen on the first day but it goes away after a restart. The issue came back on day 9 after a cold start (I believed it could be that).
My iMac is plug on a UPS and I do not remember if I had something "unusual" plug to my UPS these two days but there is a possibility that my MacBook was.

We are day 27 (no flickering since day 9 and I perform the firmware update yesterday).
My iMac was sleeping, I plug a PC notebook on the UPS and this wake up my iMac (I did not expect that). Less than 15 min after, flickering shows up and this for the next 15 min. Then I put the PC to sleep (while still plug) and I perform a sleep/wake up screen. Flickering goes away (about one hour now).

So is it possible that the flickering issue has something to do with the power? Maybe or maybe it was only a coincidence as when the flickering previously occurs only after a cold start.