iMac 2011 screen goes to sleep randomly

Check System Preferences for your Energy Saver settings. Also check to make sure you don't have a Hot Corner set up to sleep the display. Caffeine can be used to temporarily override any Energy Saver settings and prevent your Mac or display from sleeping.

Hi there,

Yes, I've developed this issue as well, started a couple of weeks ago (iMac 2011 27" i7 12Gb RAM + 2Gb GPU). It is like the screen just switches off, blanked, but the machine is still running and working ok (I can remote connect for example). Quite often happens several times in a row and is very annoying, many times I've just given up and walked away. It happens mid activity so it can't be the energy saver kicking in.

I've actually turned hot corners on since this issue started so that when it occurs I can force the display to sleep (properly) and then wake it by using the keyboard/mouse movement (easier and quicker than using the power button). It will come on after doing that but more often that not immediately blank again.

Other symptoms/things I've noticed/tried:
- The display image "wobbles" a little (hardly noticable) right before blanking
- Sometimes it corresponds with some corruption on the display itself (particularly top left corner)
- Happened in SL and still happens after upgrading to Lion
- Generally happens repeatedly once it starts
- Generally happens when the display has been in use for some time (1-2 hours+)
- Tried resetting SMC etc. with no luck
- Checked and double checked energy saver/screen saver settings and they are all good
- Only started happening after I used my iMac as an external display for a new 2011 Mac Mini connected via Thunderbolt, could just be coincidence?
- All software firmware etc. is up-to-date

Next step is booking an appointment with a Genius, however, given the problem doesn't always happen, or only happens after a couple of hours uptime I'm worried they will just dismiss it if it does not happen there and then.

Bartos88 said:

The symptoms sound the same as mine.

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Yes, certainly sounds similar. The "wobbles" are pretty subtle, so it could be what I am seeing is the brightness changing, I only noticed that for the first time this weekend and it is literally in the seconds before it blanks so there's not a lot of time to analyse it!

Likewise I was hoping the Lion upgrade would fix it but no dice. Think the only option is to take it in, certainly sounds like a hardware problem, but like I say I'm worried it just isn't going to happen in store and they will send me on my way.

I do use Bootcamp but have not noticed the problem in Windows, however, I don't use that anywhere near as much as OSX. Maybe tonight I'll try running Windows for a couple of hours and see what happens.

Might want to try opening it up and checking for loose cable connections. Its not hard to take the front panel off(held on by magnets) and then its just some screws.

Bartos88 said:

Taking a computer like this apart is not really my thing

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Yeah, not my thing either. If it was out of warranty, yeah no problem with this idea, but while it is still under warranty, no thanks.

The apple guy on the phone told me that he thought it was a software problem...

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I am thinking that too. I've been using Windows tonight for about 3 hours and no sign of the problem so far.

There are quite a few issues with the 2011 iMac displays it seems, for example here and here. While they are not the same thing it makes me think there are quite a lot of issues out there right now with the 2011 model.

I'll probably take mine in, I need to anyway as my HD is one of the ones recalled... can't help bad luck eh! Hopefully some time in the next month, I will report back here if I have any news.

Bartos88 said:

Or does upgrading to Lion preserve your files and system settings and stuff?

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The upgrade preserved everything else so that would not surprise me, but you're right it does seem unlikely a software glitch would survive something like that.

Since I am also getting the HDD replaced, I'll be doing a full Lion re-install then, so will see what happens after that.

It will be a few weeks but hopefully we'll get to the bottom of it, it's really annoying and makes the iMac pretty much unusable - except for running Windows ironically enough!

iMac 2011 screen goes to sleep randomly

Hi everyone,

Just wanted to echo that I also have the "screen goes black at random times" issue.

Other symptoms/things I've noticed:
- The display image "wobbles" a little (noticable) at random times
- Happened in SL and still happens after upgrading to Lion
- Generally happens repeatedly once it starts, like 4-5 times
- Tried resetting SMC etc. with no luck
- Checked and double checked energy saver/screen saver settings and they are all good
- Screen changes brightness (like auto-adjusting the brightness) at random times

Hoping for a solution.

Best,

Mike

Bartos88 said:

Sorry to hear you've the problem too LeSombre. Let us know if you manage to fix it

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No worries, if I find a fix, I'll let you know.

Since my post, I did set-up a hot corner that puts the iMac to sleep. That saves me the trouble of using the power button to cycle the sleep mode.

Another thing I noticed while looking for a solution is that some people recommend un-checking the "Auto-Adjust Brightness" setting located under the brightness slider, but there's no such box on my system...

Slightly puzzled,

M.

Bartos88 said:

It's probably located somewhere else in Lion.
In SL it's under System Preferences -> Displays

Click to expand...

The slider is there... Is it possible they put the box somewhere else?

M.

Well an update here. Dropped my machine off at the Apple store to get the HD replaced (as per the recall) and told them about the screen issue. They said they would take a good look at it.

Anyway, have it back now but no mention about the screen when picking it up or in any of the doco they provided so I was suspicious that they didn't investigate. Well new HD is great but screen blanked about 2 hours after starting to use it again so back to square one.

Will ring Applecare and see what they have to say. Perhaps taking it in solely for the screen will get a better result.

Any of you guys get anywhere with this issue?

Hi LagerFan at Al.

I briefly activated hot corners on my profile, and the problem became less frequent and eventually disappeared. I since then turned off hot corners and haven't seen the problem occur since my last post.

However, this morning the problem manifested itself 3x within minutes in my son's profile while using iChat.

I thought an update had taken care of the issue, apparently I was wrong.

Any of you guys with multiple profiles notice a different behavior depending on the profile you're using?

** As a side note, I noticed this morning that some permissions (access to iTunes Library) are messed up in all profiles but mine. Basically, the three other profiles on the computer can't see the shared library anymore. I doubt that it's related.

Quick question guys on something I am following up. Have either of you upgraded the RAM in your iMac's after market?

If so what RAM speed is reported in About This Mac -> More Info... -> Memory ? For example mine says:

Your Mac contains 4 memory slots, each of which accepts
a 1067 MHz DDR3 memory module.

Which is incorrect, the iMac 2011 should report 1333 MHz DDR3. So it looks like some after market RAM I bought was not as specified. Not sure if this is the problem or not but something that has come up while investigating.

BTW Had my first screen blank in Windows yesterday so this is definitely a hardware issue.

Hi Bartos88,

When I take out the additional memory I purchased it reports 1333MHz as it should. On further investigation it looks like one of the sticks I bought is actually 8500 and not 10600 like it is supposed to be. I never noticed at the time in my haste to put it in my new iMac, doh! I guess they screwed up my order.

I'm not sure if it is related to this screen issue I am but just trying to rule everything out. I'm going to run with the stock Apple supplied memory only for a couple of days and see what happens.

Bartos88 said:

Ah ok, hopefully this is the cause of your problems. I'd like to hear the result of your test

Click to expand...

Well so much for the RAM theory! Took it out and it blanked again within 20 minutes of using it with only the stock Apple RAM, back to the drawing board. On the bright side my RAM speed is now reporting correctly at 1333, so now to return the faulty stick for replacement under the lifetime guarantee.

Back to Applecare I guess for the original screen issue.