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

An update on my flickering problem ..... As I was still in my 14 days, Apple Support recommended replacement, rather than repair, so now waiting for TNT to arrange pickup, and my new i7 ordered, with an estimated despatch of Feb 1. Two weeks for them to hopefully sort it permanently.

It all packed away now, but the last few days gave me a chance to study the problem. After working for around two hours the flickering would start slowly, build up, and then start the blackouts. At one point I was getting a blackout every 15 secs. However, if I put the machine to sleep (even briefly) the problem goes away for another two hours. Heat doesn't appear to be the problem, as SMC is showing 42-49C.

Smile. Sorry for the incorrect spelling before. I don't know his personal "stats" but he is very kind and nice, that guy As far as I know he´s in Ireland probably drinking Guinness right now.

I´m expecting an e-mail from him any day (regarding my iMac).

Message was edited by: Megallis

Again, this is still interesting. I put my screen in Apple RGB instead of "iMac"colours. Have not seen any flickering since then /-:

Any one else who´s into RGB?

That is interesting & if you keep it that way, let us know the outcome. But doesn't RGB setting make the Screen look weird as far as color & clarity goes? Thanks!

Megallis wrote:
A shielding issue seems like a interesting theory. I´m in to electrics and this causes a lot of bad things. Even when you don´t believe in it. Try to solve that in the software /-:

This sound like a good theory, may be not especially a shielding issue but also an electric issue or other things like that.
There are too many variables (processor, graphic card, temperature, etc.), people who get a flickering iMac, got a second and a third flickering iMac, meaning that every iMac is faulty, or we must admit that only a few buyers see the flickering issue.
So a good theory would be to think that it is related to the environment of the iMac.

I don't know what exactly. My iMac has the flickering issue but I only see it 5 times in nearly 2 months and each time I could easily get it away by a restart or a sleep/wake screen. Each time, I was doing something unusual but each time it was a different thing (cold start, plug something on the UPS, etc.).

The "Apple RGB" settings only makes the screen a little "darker" I think. I´m not so sensitive about that. If this helps and I really don´t think so. Then all this is crazy. Please Apple, then send me a gift or maybe you need another employe

I´ll get back.

Dino, thanks for the info. MOBO (motherboard) mb?

And
Megallis:
as far as the shielding thing: 1) in audio cables this makes a huge difference. In Firewire, I don't know... same for USB. I'm not sure I've used unshielded that often, so can't say. And it's not necessarily discernible by the thickness of the cable (i believe, correct me if I'm wrong about the "necessarily" part). 2) How about a Power Conditioner! Like Audiophiles use! Has anybody put their iMac on power through a Conditioner? That would be a very interesting test I think too. Combine that with cell phones, and other nearby EMF's... interesting. Wish I could do it!.

Also, has anyone tried to make a custom profile with the built-in calibration software (System prefs> Displays> Calibrate) and looked at that? Strange that changing the profile would affect it so much!

I had my first iMac at my parents over the holidays, the second at my place over 230km away and I have the same problem with both so I don´t think that it is environmental dependent.

But if that is the case, that you have to use a Power Conditioner and remove your cellphones and other electronic gadgets from your iMac. Then at least in my opinion the computer has a faulty design and should never have hit the market.

Are we all agreed that the flickering/blackout problems comes at a time of starting a new activity (opening an application, viewing Flash website, copying files, or even waking from sleep?) and that it gets progressively worse as time passes.....and then either disappears on its own, after a period of inactivity or due to user activity (restart, putting to sleep and re-waking)? I'm just trying to narrow down these symptoms for my own sake.

Also I would be interested to know what similar conditions occur when the flickering/blackouts occur: whether or not the computer is running an *intensive activity* (high CPU usage on one or more applications?) or not? does the *TOP of the imac feel VERY HOT* to the touch? How many users also experience a *high-pitched noise* from their screen (inverter, sealant, or power supply problem?), and does that noise go away if you change the brightness, resolution, or colour setting for the display? Do any users have a *"clicking" noise* when the monitor turns on from sleep? (Mine does, am not aware that this is necessarily a problem issue but it never happened with my older 24" imac or any of the apple displays I use with my Mac Pros, so it's a little worrying).

Another symptom that newly appeared on my display is a random *brightness change (dimming)* which also disappears/fixes after putting the imac to sleep and waking again (and this is during use, not the powering-down dimming of the screen that you expect.....it's different and had a definite BLUE tinge to it).

"Are we all agreed that the flickering/blackout problems comes at a time of starting a new activity (opening an application, viewing Flash website, copying files, or even waking from sleep?)"

No, not even with stressed programs like Photoshop e.g.

My theory is that there is some (or lack of) shield that makes the flickering. Perharps it´s "bending" in different temperatures or, maybe some processor gets "crazy" after a while and the magnetics that is in there is adding to that. What do I know.

Someone reported some interesting tests with iPhone (or other mobile phone) near the computer. This is a thing that the constructers at Apple must have seen if so is the case. So probably not.

At the moment I´m into changing the screen colour settings (Apple RGB) and right now a little sleep (my own). I´m expecting the same problem soon again (read as of tomorrow) :-€

If you saw my video you could se that I had only two safari pages visible and adium.
My iMac can get very hot without any flickering at all, to me it seems very random.

My screen is dead silent, no sound and no change in brightness or colour.

Message was edited by: David.j.swe

No. Mine would start in the middle of reading a Web Page. Sometimes it would Flicker when I first booted up. Or sometimes after 10 hours of use. There was no way to make it happen & it did not matter what you had or did not have running. There was no method to the madness. That's why when I returned it, I told them Intermittent Screen Flickering.

No, mine starts whenever it feels like it, it does seem to get worse though until I put it to sleep and then bring it out of sleep. The apple store is finally going to replace just the cable, that might be the problem, I don't have the screen yellowing at least I can't see it and I am pretty picky. The cable is due to be replaced on Wed., will post after I have a chance to test it.