Greyish Smudge marks behind the glass screen.

I'm in the same position - £1640 of 27in iMac and I've got the grey marks around the top third of the screen - really unhappy about this as its a production machine (computer game artwork). I've booked into Genius Bar on Wednesday morning, really hoping they give me a straight swap for a new unit - will lose a fair bit of cash without it for a week.

Its only 3.5 months old!!!!!

Hopefully your new unit (if they give you one) won't have the same problem. Mine was only a few months old too. I'm now on my 3rd LCD and glass replacement. And I'm sure it will happen again. Sooner or later something has to give. I think Apple is eventually going to refuse to fix it anymore and blame it on my home environment. I just know I don't want another 27" iMac or any iMac for that matter. I'm hoping they let me get something else and that it's comparable in price. But probably not. I like the idea of the 27" but what good is it if it always looks filthy dirty.

If you can simply clean your iMac, then you don't have the same problem.

I get you, hopefully we will get something sorted on Wednesday - will post back but understand, after reading this thread makes me consider my purchase...

Hi,

Trip to the genius bar today, they saw the issue and said they will repair it. I said that I'm not really happy about that as its 3.5 months old and a production machine, they had a chat then agreed to swap it for a new one.

New box handed over, just restored from Time Machine and my iMac is back working perfect with no screen problems.

I also purchased Apple Care today, just incase 🙂

Super! Good move on that Apple Care. It sounds like your restore went easy as well. I hope your screen continues to be as good as new and everything else for that matter.

Off topic - never done a full Time Machine restore before, this was flawless - really happy about that.

Thanks DeepRoot

Something of interest to note about this problems, perhaps correlated with the problems. The new iMac does not run hot at all, I put my hand on the back and its only very slightly warm to the touch. The iMac that went back was super hot on the back, I'm running the same services and apps on this iMac.

Adds to the plausibility of this being burning effect.

I'm confused. I thought you already had a new iMac being it was 3.5 months old. Did you have the iMac with thunderbolt? I take it your new one does. Sounds like you may have traded up. My early 2010 iMac is warm to the touch except for some periods of times then it's cooking.

First iMac was mid 2011 with thunderbolt, this was cooking on the back. Took it back today, they gave me a like for like swap for a new one - this one is slightly warm on but significantly cooler than the one which went back faulty.

Interesting there is such a temperature difference in two mid 2011 i5 iMac's. The one with the super high temperature went faulty, not saying its evidence but it looks correlated.

did you also get the osx update in between the change....it is possible that the temperature change is due to this.

also, what i think it really is, is the following:

It is winter! My iMac 3.4 i7 (brand new) ran really hot this past summer, but now the temperatures aren't at all comparible (lower), the cool winter months really help out on that.

In any case, you cant really say it looks correlated because there are so many different variables. Just hope that this problem does not continue - and it is really unfortunate that this is one of the hugest threads in the Apple community and there is no sort of official response from Apple! They should really publicly address these things....

Bill, Hi

I think its comparible and an intersting observation - my iMac was exchanged today. I'm not getting confused with seasonal temperature changes, the temperature in my house is always around 23 degrees C but regardless, yesterday I felt the back of the faulty iMac, it was really hot to the touch. Today I check the back of the new iMac and its significantly cooler - the temperature in my house is still 23 degrees C.

Both iMacs are running Lion 10.7.2, I have the same apps open today - yesterday core CPU was 46degC, power supply position 2 was 59degC, GPU was 61degC which all seem in spec.

The new iMac is running core CPU 34degC, ps position 2 46degC and GPU 43degC

Ambient temperature according to the iMac is 23degC

Not massive differences however significant differences to touch the back on the iMac.

Apple Genius said they have not seen this before however he was aware of this thread, they agreed its very poor for that degree of failure.

Sophos09,

Thanks for the full detail. It is exactly what I was looking for. However, if it is the case that your new iMac has something different in it that makes the iMac run coller, then we should all benefit from this with a recall or some kind of responsible notification from Apple before any potential probems.

When someone spends over 2 grand on a system and uses it professionally and for what it is advertised for and there is such an uproar of a specific incident as above - it should be formally handled by the Apple people.

...again thanks for the in depth detail.

(By the way I have a small external desk fan pointed to the back side of my iMac - it helps a lot!)

Bill, Hi

Agreed, its not good however when you compare annual iMac sales against total amount of failures I'm not convinced Apple would consider a recall. Would be interesting to know how many iMac units have been sold per annum.

I also agree that it *** for the customers that do experience this problem, to them it does not matter if they are the only person in the world to experience it, they need it sorted - in my case, Apple were perfect it finding a resolution by giving me a new iMac, it meets my nominal value as a customer and why I buy Apple 🙂

Dude I completely agree with you.

Whether it is a sound business decision for Apple or not is a whole other discussion. I guess they handle the issues well through the warranties as you said!

(My only point is that it does seem like a fault of some kind - in the design, but then again if they were to admit it, it would cause a media **** storm....hehehe)