http://support.apple.com/kb/HT2807
They called this "image persistence"
Sleazy. Sorry, there is no other word for it.
The HEAT from these iMacs wears out the LCD screen more prematurely.
Apple needs to fix the problems - historically, iMacs get very hot. It's a poor design compounded by sloppy manufacturing, if thermal grease is slopped onto iMac CPUs as badly as the treatment accorded MacBooks is (iFixit)...
The 2009 iMac I sold had the buyer emailing me 2 years later, saying how his screen burned in imagery and was glad I had the extended warranty...
What Apple states is not a total fiction; LCD screens will slow down after a while - I've seen 8 year-old monitors start to retain patterns... but that's EIGHT YEARS. Those monitors are properly cooled to begin with, and don't have miniature toasters heating up the innards.
Backlight type (LED, CCFL) makes no difference. LCD screens' output depend on millions of transistors opening up to let light through. CCFLs don't last as long but - during the more optimal part of their lifespan put out a wider gamut. LEDs cost less, use less electricity, but have a narrower gamut (the higher end/whites being affected worse...)
27" ACDs might fall into this HT2807 as well. It's the same display, and it gets warm, but there are no computer components nearby. Both iMac and ACD have pathetic heat channels and small grilles, with the latter having no active (fan) cooling involved.
And if a $1000 quad-core standard Windows laptop can be engineered and cheaply produced to remain under a certain temperature (e.g. 75C under full load), so can these Macs -- especially given the cost. Right now, only Mac Pro towers I'd rely on for anything long-term and long-lasting. Those legitimately ARE quality-built, but it's easy to see why Apple wants to ditch them. Most of their money comes from iMacs, MacBooks, and iPhones... and heating ensures planned obsolescence.
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Glad my TV doesn't do that.
They're wider, with more grilles/vents (and at the top with no shroud). They get warm, but not enough to adversely affect the display within such an embarrassingly short period of time.
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My rMBP with the LG panel indeed suffers from image retention. But: the only way to actually notice it is to have a checkerboard pattern on the screen for around 20 minutes and after that switch to a dark background. I have been working with this machine for quite some time now and so far, could't find a situation when it was actually an issue (or even detectible) during my normal usage (both in work and gaming) - and I usually have static UIs, like TextMate, open for a long time. If all the other machines are like that, then I honestly don't know what people are complaining about.
I forgot about that; the Retina issue being a different situation... the article I read from someone else posting the link is about iMacs... IPS screens tend to be slower with response time in general. Such ghosting would not surprise me, at least for motion video. Burned in/totally retained imagery is my worry. If the pattern clears within a few seconds, but such high densities of transistors could be an issue long-term... Newer generations of Retina will doubtlessly improve...
And it's LG. Most of their products are not always first-rate. Doesn't matter if another company buys their products and puts on a different label. A skunk sold by any other name still smells the same...