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

I downloaded and installed the Apple Graphics Card Firmware update, but unfortunately it hasn't worked on my i7....

Just a post to inform that I called Apple to have a refund on my week 50 imac 27" i7 that I ordered on the applestore. I'm in Paris, France. I'll just wait that things settle down, using my old G5...

No problems for the refund.

Clearly, for some people’s machines heat does seem to be a contributing factor.

There may be a pattern emerging in these posts. Computers in which the problem seems less sever tend to be affected only after considerable use, once they’ve generated a fair amount of heat. In more sever cases heat doesn’t seem to play a role. This may be an important clue and following clues is key when troubleshooting problems.

One hopes that the people troubleshooting this particular problem aren’t so eager to overlook important clues just because they aren’t consistent with their own personal theories.

I received my third defective iMac day before yesterday.

The first one had the intermittent black screen / split screen issue on day one & four (went back on day four).

The next had no Airport card installed (went back that day).

The latest arrived day before yesterday. It came with the firmware update installed, but did a lot of flickering last night, and blacked out 4 times. It's a 8952, shipped on Dec. 26.

Sigh. I'll be calling Apple this morning.

Sheesh...

Doesn't apple turn these computers on after they are assembled, and let them run a suite of tasking programs to make sure they are ok before they are boxed up for shipment?

Isn't there any QC on operations?

I do suspect the problem is heat-related as well. I purchased two 27" i5s in the week before Christmas. The one that started exhibiting the problem is the one running Parallels and a Windows Server 2008 VM that was keeping the cores quite busy. Watching iStatmenu on both, the flickering Mac had hit 127 degrees, while the other stayed in the 110s.

During the call with Apple, the rep made it sound like the patch may be effective if it is applied before damage is done, but if whatever happens has already happened, the patch won't bring it back. Of course, I do not put a lot of weight on the phone reps understanding of the issue, though the two people I spoke with actually seemed quite bright.

I don't think the problem is heat related. At least not for me. My screen started flickering shortly after it was awake from sleep. Room is very cool. Was only surfing. On the other hand I've stressed the machine with all kinds of tests running all cores at 99 % with flawless results.

Cuenlain wrote:
Clearly, for some people’s machines heat does seem to be a contributing factor.

There may be a pattern emerging in these posts. Computers in which the problem seems less sever tend to be affected only after considerable use, once they’ve generated a fair amount of heat. In more sever cases heat doesn’t seem to play a role. This may be an important clue and following clues is key when troubleshooting problems.

One hopes that the people troubleshooting this particular problem aren’t so eager to overlook important clues just because they aren’t consistent with their own personal theories.

Since you decided you'd condescend to me, let me see if I have your theory right:

More heat = less flickering
Less heat = more flickering

And you think that's a sensible clue? If we follow that pattern to its logical conclusion, then if we make the computer nice and hot, the flickering should go away, right?

The problem with this issue is that there's no common, repeatable pattern that sets off the flickering. For some folks it's one thing, for others it's something else.

Rather than me rejecting a "clue" out-of-hand, perhaps you're trying to force a pattern onto a set of random and/or coincidental events?

I also don't believe it has anything to do with heat. My computer is off overnight and I turn it on in the morning and it starts. Note to APPLE TECH -- If by far chance they actually read these posts -- The flickering goes crazy when I transfer files from (not to) my back up drives, when I am installing software and watching youtube.

At first, my last Mac with the fried video section would fault with no rhyme or reason. As time progressed though, the faults were far more frequent. Even first thing in the morning - I had about 10 solid minutes before it would act up. I think as the problem got progressively worse, its heat tolerance dropped. I.E. it's possible that this is still a heat issue. I'm just going to keep my eye on the thermal reading and see what happens. If it starts to flicker at far lower temperatures, then maybe it's not heat.

Heat makes many hardware problems worse, and Apple has a long history of iMac heat problems (though the cooling in the new iMac is pretty impressive). So it's reasonable that heat contributes. Maybe there are heat spikes that cause damage to the card too (which is why I installed the firmware update even though my early flickers have not recurred).

I think there are probably several problems contributing to video distortion on these displays, all of which end up causing various kinds of video distortion. Heat contributes to some, but not to others.

I really doubt we'll solve this mystery here. I suspect Apple will need to fix several things to get it under full control.

I think the flaky display problems are due to sloppy assembly and lack of QC to catch the slop. That would explain why some have problems and others do not. The yellow tinge could also be explained by sloppy assembly...loose or badly fitted connectors, et cetera.

Sorry if I wasn't clear

More heat = more flickering
Less heat = less flickering

at least in my case, and as it appears from the posts, the same with many others. In complex situations it isn't logical to discount anyones experience and especially not the experiences of a significant number of people.

Heating hasn't been completely ruled out as a contributing factor in the flickering, however, it is not likely the cause since so many have the issue at lower temperatures.

That being said, one thing many fail to consider is the fact that the iMac sensors only monitor key areas within the unit. There may very well be undiscovered hot spots, not covered by sensors, within the unit that may contibute to the problem, particularly in the power supply which can spike at startup, heat rapidly, then cool down just as quickly.

Unmonitored areas, particularly those within the display can have temperatures well above that shown by the sensors, especially connections and solder joints. As the heat spreads, the sensor picks it up, the fans kick up higher rpms, and the area may cool briefly before repeating the cycle.

In a 27" monitor, where do you place the sensor? Even multiple sensors would leave some areas unmonitored, and given the compact design of the imac, the heat could emanate from any of the devices adjacent to it, hd, op drive etc.....

Hello all,

Not to long ago I had screen problems with my old g5. It turned out there were a bunch of bad capacitors on the main board as well as in the power supply.
The problems I read about here sound much like what I saw on my machine. Could it be that..