27' iMac (2011) Screen turns off

I bought a LED Backlight Board from ebay, all worked fine for me, easy to install, youtube had a video of it

Did you get your iMac sorted? Worthwhile contacting your local Apple shop & talk to them about the EU Consumer Laws. (Apple do publish it on the website under guarrantees) Good luck!

For what it may be worth, here is my experience. I have a mid-2011 27" iMac. Under OS X 10.6.8, I never had any issues with the display. I didn't upgrade to Lion, but I did upgrade to Mountain Lion. For me, that's when the issues started. I started a thread about it here ( https://discussions.apple.com/thread/5148923?answerId=22865181022#22865181022 ) but never gota resolution. Even after upgrading to Mavericks, the issue persisted. I noticed that if I didn't let my iMac go to sleep at all, that would help the issue somewhat.

Reading through this thread, I thought I would comment on my personal experience with some of the possible causes.

Temperature: For me, this was not an issue. My iMac is in a room that is anywhere between 70-80 degrees Fahrenheit and I've had the iMac display randomly turn off independent of the room temperature. That is, keeping the room cooler didn't keep the iMac display on.

Video card: This too seems to not be the issue for me. I have two external monitors connected to my iMac and when the iMac display goes blank, the two external monitors work just fine. There's no hiccup or anything, just the iMac display going dark. Additionally, I took my iMac in to the Apple Store (by the way, the 27" iMac is a pain in the butt to lug around!) for the 1TB hard drive replacement program and also for the AMD GPU replacement program. The hard drive was replaced, but the Apple techs said that the GPU was not eligible for replacement because it didn't fail when they ran the diagnostic. They said they would only replace the GPU if it failed under a specific test.

Backlight: This did not seem to be the issue for me. When my display went black, even if I shined a flashlight into the iMac display, there was nothing. I couldn't see a faint trace of anything, it was just black.

Software: So far, in my case, this seems to be the most likely culprit. I did a clean install of Mavericks after getting my iMac back, and it's only been half a day, but so far, my iMac has been able to go to sleep and wake up with no display issues. Previously, upon turning on my iMac, the iMac display was guaranteed to intermittently or permanently (for that boot cycle) go black within an hour.

Previous to doing a clean install, I tried all the normal things to fix the issue, including repairing disk permissions, resetting the SMC, unplugging external displays, etc...but none of those worked. So for those of you still experiencing this issue, as much as a pain it may be, a clean install might be worth a shot.

If the problem returns for me, I will report back.

Aaaaaand, the problem has returned for me. #*%&#@*(@(!*@*$#)@((@&$^

If anything, the problem is now worse for me. My current and previous energy settings are that the computer never sleeps and that the displays turn off after 30 minutes. Previously, at least if I stopped my system from sleeping, the iMac display would work until the next restart, meaning I could get at least a few weeks of use on all the displays. Currently, the iMac display never turns on when I start working on the computer, even though the system wasn't sleeping (the displays turn off but the computer doesn't go to sleep, which is the same setting as before I did the clean install). The iMac display will turn on at some random point (usually after I've been using the computer for an hour or more) and then stay on, but once the display turns off (overnight, for example), it won't turn on again for at least an hour after I start using the computer again.

All of your symptoms were indentical to mine and I tried EVERYTHING to fix it.

My realization?

RAM

I have 4 slots open in my 2010 - iMac

2x2GB DDR3-10600
2x4GB DDR3-10666

For some reason, my iMac couldn't handle both together. At first I thought it was the 10666, but then tried both RAM types separately, and both work.

I guess you shouldn't pair 10600 with 10666 - or at least different ram sizes.

I am going for 4x4GB 10666 now.

I hope this helps everyone because I was losing my mind for a short while.

iMac is happy and on full brightness.

Life is good.

Well, I used my Apple Care and the whole screen and display electronics were replaced. The system is now working as expected.

Nothing else seemed to work.

Sunfiresaturn wrote:

All of your symptoms were indentical to mine and I tried EVERYTHING to fix it.

My realization?

RAM

I have 4 slots open in my 2010 - iMac

2x2GB DDR3-10600
2x4GB DDR3-10666

For some reason, my iMac couldn't handle both together. At first I thought it was the 10666, but then tried both RAM types separately, and both work.

I guess you shouldn't pair 10600 with 10666 - or at least different ram sizes.

I am going for 4x4GB 10666 now.

I hope this helps everyone because I was losing my mind for a short while.

iMac is happy and on full brightness.

Life is good.

Being desperate, I decided to try your solution so I bought 2x8GB sticks and replaced the RAM in my iMac. So far, so good!! 😀🙂😀 It's been about two weeks now and I've been running it with the computer not goign to sleep at all. Starting next week, I think I'm going to try to have it go to sleep after inactivity, which is how it was before this whole saga started.

I never would have thought about the RAM being the culprit. Thank you SOOOOOO much for your post!!!

I had a similar problem to many on the issue, including yourself, of the screen shutting down randomly. It would just go blank, sometimes with very thin green vertical lines visible but not always. I booked an appointment with Apple and duly took my 27 - inch, Mid 2011 iMac to the store. The Genious hooked my machine up to thier 'test kit' and ran a diagnostioc check which took a couple of minutes. The result was that there was an isue identified with the graphics card. The Genious explained that there were problems with some cards on machines built at this time and said it needed replacing. I agreed to this and left my Mac with them. I collected 7 days later, no charge, all is now fine. Incidentally this is my fifth Mac and only the 3rd hardware issue that I have had in 26 years!

Hope this helps.

Same problem,

Someone has got news or solutions ?

Max By wrote:

Same problem,

Someone has got news or solutions ?

Have you tried the various methods mentioned in the thread? Replace RAM? Replace GPU if it falls under the replacement program? Replace LCD if under AppleCare?

My mid 2011 27" has so far been at the genious bar 3 times.

1. Blamed non App Store software, wiped my drive.

2. Replaced my video card under the quality program.

3. Replaced LCD panel.

Only had it back a couple of weeks and today the back light turned off again whilst in the middle of watching a video clip.

Getting really tired if all this. The problem has been the same for over a year now but thankfully Apple has not yet charged my a cent. They have in fact been really helpful.

llubnrut wrote:

My mid 2011 27" has so far been at the genious bar 3 times.

1. Blamed non App Store software, wiped my drive.

2. Replaced my video card under the quality program.

3. Replaced LCD panel.

Only had it back a couple of weeks and today the back light turned off again whilst in the middle of watching a video clip.

Getting really tired if all this. The problem has been the same for over a year now but thankfully Apple has not yet charged my a cent. They have in fact been really helpful.

Have you tried changing the RAM? Sunfiresaturn mentioned it fixed the problem last month and I posted two weeks ago that it fixed the issue for me.

Hello !

I sadly join the "black screen but iMac still running" club with my mid-2011 iMac 27 (3,1ghz / HD 6970m). The issue appeared for the first time immediatly after I upgraded to Mavericks :

- the screen shutdown after 10-20 min when I'm running Mavericks

- the screen shutdown after 30min - 1h when I'm playing demanding games under windows 8,1 / Bootcamp

My guess is that it is linked to my upgrade from Lion to Mavericks (it never happened before) and it is somewhat linked to the temparature (the mac gets hot, I can feel it whith my hand, but the fans won't speed up like they did before the upgrade).

So I will try to remove 4go of RAM (I added 4 go to the 4 go that were sold with the iMac), but I'm not convinced it´s the source of the trouble since they're in the iMac almost since the beginning, and the screen shutdown appeared only 10 days ago when I installed Mavericks.

I qualify to the 6970m replacement program, so that may be a lead too.

One more thing : I installed Macericks (clean) on the internal HDD, but before, I was using an external thunderbolt SSD to run Bootcamp. Maybe it is linked too but I doubt it.

Daffodil

@Jah_Daffodil:

Please do report back and let us know if the RAM was the culprit. If not, any other attempts/fixes would be greatly appreciated, thanks!

On a side note, it has been almost two months now, and I haven't had any issues with the screen going black. It looks like it was the RAM for me. Which is still odd, because the issues coincided with me upgrading to Mountain Lion, but I guess it was just a coincidence.