Greyish Smudge marks behind the glass screen.

You can't really compare an iMac monitor to an LG refrigerator. I live in a country with a very temperate climate and still have the grey smuding problmems with my screen.
I don't smoke and wouldn't say my home is particulary dusty or humid. So enviromental problems is not a factor.
Sorry to disappoint you, but the smudging on your screen will in all likeliness return some time in the future and get worse.
I'd lodge a complaint with Apple as soon as possible and start the long fight to have your monitor replaced.

I agree with you on the first paragraph. My iMac has been in two different climates and kept clean and dusted only to have this happen twice in just over a year. In my case it most defiantly is not moisture but a defect in the monitor or the manufacturing process. It did not "come & go" like others have experienced or try to say is the only thing happening. Mine started getting discolored and progressively got worse and wouldn't disappear if my computer was asleep or off. It was there if my computer had been turned off for a day and just turned on.

I don't agree with your second paragraph as I've had my iMac repaired both times no questions asked and within a week. I do have Apple Care though.

This is the part for me where MY paragraph 1 divided by MY experience in paragraph 2 equals my biggest issue with Apple "computer" right now. They fixed my computer, but before this I never had to get a computer purchased from them repaired.

And just so you know rockjano3:

I've taken my iMac to two different Apple Stores in two different cities to be repaired and at both places the Geniuses had no explanation and said: "I've never seen this before."

Sure they haven't…

I am in Hungary. We don't even have a real Apple Store here. :-( (apple just does not care of my country)

I took it to the service they told me that they know about the problem and Apple is willing to change the LCD unit even after the one year old guarantee period but only if the machine is not older than three years.

Mine was just about two month older :-)

So it really *****. No more iMac that is for sure, just maybe a mini and cheap 27" korean monitor from e-bay. Same screen than in the Cinema Display for a fraction of the price...

Or a Dell U2713HM.

I insist to the 2560x1440 pixel resolution.

The new mini's are good enough.

Or ...it might be a hackintosh machine...who knows :-)

I am also fed up with apple

rockjano

I took my 27" iMac into an Apple Store in the Houston area and they said the gray smudging is a "known issue" and they had the display replaced by the end of the day. They also replaced the GPU which was causing a totally different problem. Since my extended warranty ends next week, I'm taking the iMac in again tomorrow to have the optical drive replaced before it's too late. I've been very happy with the service I received.

PS. I've downloaded the Temperature Gauge Pro fan-control app to keep my system from frying itself in the future.

Well, if it helps any, my monitor actually started looking better after I installed the fan-control app and before I took it in for repair. I had streaks going up the right side of the screen that disappeared after a short while. I'm glad I photographed the problem when it was bad and printed up the photos beforee I went to the Genius Bar. Maybe yours will start looking a bit better.

Hmmmm... thanks that sounds promising...

Which is that fan controlling soft???

I also noticed that when the mac is cool that the problems disappear and as it gets warmer it gets stronger.

Probably it is still some LCD problem but if that helps....???

I also took out the DVD drive from behind the LCD (where the problem is) and put an SSD in the place that also could be problematic.

Thanks

rockjano

I set it to manual control and keep the fans running just a little faster than normal at all times. The increase in noise is minimal. Then I up the fan speeds even more when needed. I don't use their automatic setting. Maximum fan speed is just overkill and way too noisy.

As the grim reaper of the community I would like to say this discussion has surpassed any that I can recall the iMac issue is based on your LCD type point blank period there's not a reliable workout around other than replacement relying on a program install fix will not work despite and yes it is a temperature issue the SAMSUNG LCD circa aren't effect quite like the LG LCD circa regardless it was a mixture of a bad build and a company that even though I know I'm in a room full of die hard Macintosh users as I am included I'm sure clearly knows and knew of this issue at hand but had to push the envelope probably around its discovery with this being said I would sale your machine even though I know this sound outrageous as I did because you'll continue to encounter this problem

Not to mention in my case the heat problem will also eventually over power your BT Module as well as other internal components but if this isn't what you want to hear or can't visual doing such as continue to discuss this problem and I'll bet 10/1 this will continue until infinity and beyond

P.S. MERRY XMAS TO EVERYONE ABOUT THE COMMUNITY SO LONG until next time

Makes me mad!!!!

Otherwise it is such a great machine. Especially that I replaced the otherwise very inreliable DVD drive with SSD, it is like a new computer. It is just soooo much fast than before. Even when I open file from the old HDD it is a LOT faster.

All the DVD drives die sooner or later I think they are just not designed to work in vertical position. (no other computer uses DVD in vertical position)

I use an LG BluRay writer for 3 years and it is just great (faster-better)

rockjano

Haha I think so much I believe my brain has created its own OS but hey it's hard being an evil genius @ the Genius Bar needs to display a liquor license cause they seem to be always be intoxicated full of misguiding,and unreliable advice. I have a secret / come closer, closer, closer always call corporate directly to discuss your problem for apple care for whatever reason in store personal really aren't geniuses but actually college kids working for the summer / then he died end if movie roll the credits

Well i tried it 3 days trial period... well it did not change a lot. The shape of the smudge might changed a little :-)

It only helps if i really turn on the fans which is noisy and probably the fans will die sooner as well so it does not really worth it...

Like I stated I'm not the best at explaining more or less a hands on type but as stated in my encrypted prior post clean it up

And put it in the market I would

Hate 4

Your iMac to be a beautiful money pit I know this you know this and apple definetly knows

This @

Pick

Your battles

Wisely

Rockjano by golly I think you have solved the equation ultimately switching to an ssd would surely reduce your heat consumption internally thus reduce heat I sorbed by LCD thus our closest work around for the LCD issue trust I'm very sure it's a heat issue but temperature wise I am not clear originally I would start up and my smoke screen would appear and after warm up nothing other cases I've heard the opposite so who's going to give it a go

I already put an SSD in the place of the DVD drive (which was dying as well) But I need more space so I needed a regular HD as well a terrabyte one. I wil buy a new one and put it into. I am pretty sure that the dying HD was overheating. Dust also could be an overheating factor. And that smudge was sign of the overheating. Yes if the mac was started cold it took some minutes to appear. So it was defenatly a heating issue..

rockjano