Q: 2011 core i7 27" screen flicker at low brightness

I thought I had fixed this problem but it is still continuing. Apple has replaced the led backlight power module and it still flickers. All fimware updates installed...still flickers. Wiped hard drive and reinstalled the OS. Still it flickers. I have a late 2009 model 27" screen. I now strongly feel this began after updating to 10.6.8. I'm no programer or expert but I believe 10.6.8 isn't playing nice with the updated firmware.

I have a 2009 27" iMac (i7 8Gb 2TB - pretty much the top of the line when it was bought) but am now starting to get really disapointed with the screen.

It seemed fine up until a few months ago when one half of the screen appears noticeably darker than the other half.  It seems to sometimes rectify itself randomly then other times it doesn't.  When I turn the brightness down I can hear an audible whining noise coming from the screen, then when I turn it down all the way the bottom left corner of the screen flickers between 0 and 1 on the power gauge.

I can obviously still do what I need to do on the computer but for a £2000 piece of kit I would expect it to work perfectly.

I'm well outside the warranty period - do you think the guys in the store would be able to fix it if I were to bring it in?  It's a massive hassle to transport it around so if a software update can be put out to address it then that would obviously be much better.

Same problem Here.

iMac 27" i5 Mid 2011.

This is not called Flickering.

Is just like someone pressing F1-F2 on my Keyboard. The Brightness makes a little bit variation automatically from dark to brigh and the reverse.

Its not very big problem, but for a machine that costs 1600Euros, is...

I have the exact same problem as Lafas1987 describes. My iMac 27" i7 is from late 2010. I upgraded to Lion when the 10.7.2 version was released.

Same problem. 27" iMac i5 July, 2011.

Even when I have the brightness all the way up, I still see it. I haven't upgradaed to Lion yet.

I've the same problem and sent the iMac to apple's support. As my iMac returned i was absolutly shocked. The iMac was absolutly dirty and the problem wasn't fixed. Because i dont wanted to send the iMac back to Apple's bad support i went to the Apple Store in Oberhausen an they tried to fix it. After one week i got my iMac back and they told me that the iMac isn't flickering. At home i recognized that they haven't repaired it because the problem is still there. Back in the Apple Store i asked for a replacement because the iMac was only three weeks old. At the end they "suprisingly" said that the iMac is not flickering and absolutly ok. It's a shame that apple can't help me with my problem.

I started experiencing this about a month ago on a 27" iMac 3.4 GHZ Intel Core i7,

Graphics  AMD Radeon HD 6970M 1024 MB running 10.7.2

It isn't much of a flicker, more like someone else stated of it being a very slight continuous dimming and brightening, but for me only happens at brightness level 4. All other levels are fine. I do say that it is very subtle, and hard to notice for most people, though I can pick up on it. It'll be fine for a while, then will do it sporadically.

I bought the iMac in September of 2011, and came pre-installed with Lion. It is a custom built.

Yes I have the same problem, as if somebody is pressing the brightness keys.  I have rang Apple and reset the memory, but still nothing.  My machine is still under warranty so that is lucky, but for a machine which cost £1000 it's not very good. 

I hope you are reading this Apple because an update to this would be very much appreciated. 

I want to buy from Apple in the future.  Come on Apple, you're better than this.

Many thanks

PS Could this be a keyboard issue?  Has anybody else tried the same machine with a different keyboard?

i have the same exact issue as albe75. raising it to 5 or higher seems to do the trick.

Yup Same problem 2011 i7 3.4GHz 8Gb RAM 10.7.3

Had the same problem when I first bought last summer, two screen issues - flickering in low light levels and weird problems with Finder window becoming corrupted.

They switched out the LCD and that seemed to fix it.

Does appear to occur in low ambient lighting levels.

Not sure if this will help anyone else but it worked for me because Im retarted lol. Basically this happened to me for a while and I started to realize it only happened when I moved my mouse quickly into the top right corner. Turns out I had it turn on the screen saver in that corner in my Hot Corner settings. Hopefully this helps someone!

Glad I found this post ( had to search for just the right terms) as I was starting to think it was my eyes and the flickering wasn't really there.

Like many here I didn't want to take it into the Apple store as it's not so noticeable under bright light, so I feared they wouldn't spot it.

However, taking the suggestion of moving the screen brightness fractionally up has fixed it - looks like there's just a sweet spot in the power unit that causes flickering that's just visible at a certain point. Screen is slightly brighter than I'd ideally like, but it's better than the annoying flicker out of the corner of your eye!

27" 2011 iMac for interest

I am having the very same issue on my

27" iMac 3.4 GHZ Intel Core i7,

Graphics  AMD Radeon HD 6970M 1024 MB running 10.7.4

I bought the computer about 6 months ago and I started to notice the problem about 2 months ago.I called Apple and followed all what they recommeded to do, including reinstalling OS which was a pain.

i don't seem to find a pattern to the flickering but something new just happened, the screen got darker about 4 notches. I restarted and still was darker although the brightness levels bar remains the same at the brightest point.

I do photo retouching and certainly a screen that is not consistent (colour/brightness) is a problem.

Has anyone hear anything new about this problem? Phone support said they couldn't exchange my machine because it does not 'seem' to be a hardware problem... What to do then if there is no software fix?

Thanks.... Getting progressivly mad here!

Is there a new Graphics firmware or talks of releasing one for this problem?

I've got the same problem with my 21.5" iMac. The screen only flickers on the lowest brightness ("one bar") or when the screen dims after not being used for a short amount of time.

Because it's all otherwise working perfectly and I don't really want to go through the hassle of taking it in for repair I've decided to just put up with the issue.

I've also got around ever seeing it by turning off "automatically reduce brightness before putting display to sleep" and setting the screen saver to come in after 5 mins. Not ideal but a workaround of sorts.