iMac screen goes black, but system runs fine in background

StefanoDG,

I have done the exact same thing. Twice took it in to Genius bar. Twice they were unable to reproduce the issue.

At this point, we are going to continue to use th iMac, then when it occurs, Video record it. The iMac Logs do not capture the issue. It is completly hardware Video Related. But we seem to be able to cause it to happen by upping the brightness to max and streaming videos. THen it will occur 3-4 times in a row.

I had one "Genius" at Apple tell me that 'it's an environmental issue, since we cannot recreate it here."

LOL. Idiots. I've worked in IT for over 8 years. This kid must be freash from Taco Bell or something.

As long as I have it under warranty, I'll keep coming back..

I was plagued with this problem for about a month with increasing frequency.

I tried many of the things mentioned here with no success!

Reinstall the operating system and have been problem free for several weeks!

Try it! It doesn't cost anything but time!

I am experiencing the same problem. It gets worse and worse. Must do the Option-cmd-Eject trick every minute or so. Cannot work like this. All hardware tests come up negative. Will now reinstall and see what happens.

In the meantime it seems a bit like the screen saver has gone haywire. I now must do the option-cmd-eject trick every other second. Just need to finish this backup update. Then reinstall.

I've had this problem on my mid 2011 27" iMac for some time now - maybe a year. I get over it by keeping the brightness down at 3-4 clicks–any higher and it will blackout on me, once it warms up. I also set up a hot corner (in Mission Control) which is set to black out the screen. When the screen overheats and goes off, I just move the mouse to the Hot Corner then back out and the screen invariably comes straight back on.

A bit more convenient than sending it to sleep with the keyboard.

Rather than using SMC FanControl I use the free and much better SSD Fan Control from exirion.net which seems to help.

http://support.apple.com/kb/TS5167

I have the same problem, the genius techs couldn't identify it, said it was a 3rd party software glitch. If you have a mid-2011 model with the AMD Radeon HD6970M video card, this is likely the fix you need.

(click on the apple, upper left>about this mac>more info to see if this matches your hardware)

http://support.apple.com/kb/TS5167

looks like this could be you, mailje.

Tropical John! Ima rush home and find out if this what I have. Thank you for sharing!!!!

As those above have expressed... I have a 2011 27" iMac which has the same intermittent black out problem. I've taken it twice to the genius bar for complete tests over a couple of days.... you know, those diagnostics that we don't have access to. They found nothing... I'm at my wits in.

Here's the problem though with the replacement video card program problem..... Apple won't replace the video card unless they can see it has a problem. This is what they told me at my local Apple store. So... until I can show them the problem, they won't replace the video card.

However.... I'm starting to have my doubts that it's a hardware issue. I'm curious if somehow Adobe flash isn't doing something. Maybe it's a Mavericks bug... I just don't know. I have tried everything except reinstalling OSX. If that is the solution... then it's a software problem and Apple should be aware of it and fix it with an update.

I really need to upgrade my iMac, but I just can't buy another iMac if there is an inherent design flaw. The Mac Pro is just impractical for me... and the Mac mini is a 3 year old design... doesn't even have USB3!.

Obviously.... not a happy Apple customer at the moment.

Hi All,

I had the same issue of my screen blacking out after a while but the rest of the system still seemed to be operating (since the keyboard light was on etc.).

However I managed to find a link by apple which solved my problem (at least for now;)

Suggest you check it out if you have a MacBook Pro 15-inch, Mid 2010 model:

MacBook Pro (15-inch, Mid 2010): Intermittent black screen or loss of video

I have the same problem and tried many suggested fixes. Apple couldn't find anything wrong when I brought it there.

I've had to work on the 3rd display level for ever because it would always go black and I'd have to do the shift + ctrl + eject to wake it up.

HERE'S MY SOLUTION: Go to System Preferences > Displays... Keep the Displays window open. That's all! I have the brightness all the way up and it hasn't turned off yet!

Hopefully that works for you guys (and continues to work for me!).

FYI.. I have iMac 27 inch, mid 2010.

Processor 3.2 GHz Intel Core i3

Graphics ATI Radeon HD 5670 512 MB

Software OS X 10.9.4 (13E28)

Hi MN, My solution was to go to "System Preferences/Energy saving/turn display off after" and change the time to "Never". I note that the display would darken before turning off.

hello,

have the same problem with my imac 27 (11.1) late 2009 with ati 4850. My screen keeps "locking" and goes black

but still the system is running. the only decent solution i found was to keep the brightness as low as i could as mentioned in previous post. if i attempted increasing it immediately it started going black again.

I tried yesterday the procedure with replacing the graphic card's kexts with the 10.6.2 ones and became 80% more stable. i now have the brightness at 60% and since yesterday i had only two locked screens instead of 50 that i was having with the mavericks kexts. So it's not completely fixed but surely works much better. And this is the reason i believe that it's not a hardware problem, but a bad drivers/software thing... To make this statement stronger, many say that if you try installing windows on the imac, you'll see that there would be no problem having full brightness and no black screens. Havent tried installing windows but probably i will just to check it by myself.

the procedure replacing the kexts it takes about 1 minute with the kext helper and you can find it here: http://www.pauloamgomes.net/blog/fix-weird-os-x-freeze-imacs-late-2009

dont worry it's not the same problem. i really saw much better stability of the problem after doing that, but not a complete fix.

Hi I had the same problems, I used a second screen with thunderbolt cable, works great, I now have taken my mac to the shop where it was bought from PC world, 27 iMac 2011 they fixed FOC thought the https://www.gov.uk/consumer-protection-rights i.e. apple paid them to fix it for free. Thanks Apple your the best, will never buy a mac product form a pc shop again 🙂

I found this solution on another web site. I went System Preferences..Bluetooth...Advanced and unchecked the box "Allow bluetooth devices to wake this computer". I was skeptical at first but so far it's worked in my situation. Hope this can help someone!

Hi,

I have the same problem (Imac 27, mid 2010, 2,8 GHz Intel Core i5) and tried a lot of the mentioned things but nothing works really. At the beginning I could sometimes work for days without a problem and actually the display is black even if I boot the computer. I used a second screen with the mini display cable. That works but is not really a solution for this problem:(

It seems that a connector is loosely connected. (post from user "12Tarona")

http://forums.macrumors.com/showthread.php?t=1375427&page=2