imac 27" 2011 random black screen HELP!!!

My iMac goes black screen also. The only way I can restart it is by pulling the power cord from the back of the machine, wait a bit, then plug it back in and reboot. It happens daily sometimes many times. HELP

Have similar problem:

1. Ran extended hardware test. No problems reported.

2. Under system prefs, set computer and hard drives to "never sleep." (Black screen seems to happen, though, even with default prefs.)

3. Also set screen to not automatically adjust brightness. (LED screen also sometimes dims then brightens randomly. Don't know if related issue.)

4. Have reset PRAM and NVRAM

5. Have rest SMC

6. Have monitored temps. GPU diode and GPU heatsink never over 140 F., usually in the 120s to 130s

7. Had the screen go black 4-5 times in an hour this afternoon. Other times, no black screen for extended number of hours.

8. Pushing the power button does nothing at first. Only when the internal hard drive spools down/off does the button relight the screen/computer. At first I thought an external USB drive was the issue. But the black screen occurs even if the external drive is turned off. Pushing keys to "wake" the computer does nothing.

9. Have installed the recent WiFi and Firmware updates for late 2011 iMacs

10. Have repaired disc permissions and verified hard drive

11. This problem has only started within the past month, so am wondering if it is connected to one of the recent Lion updates. No problem like this between August, 2011, and January, 2012

11. Nearest Apple Store is 130 miles away, so would prefer not to have to take it in

I'm having the same problem but mine started 1 month after the warranty expired in April, 2012. I also live quite a ways from an Apple Store so don't want to go back and forth over this problem. I'm not as computer savy as you two guys and this is my first IMac so wouldn't know where to start anyway. I do know that this didn't start until a couple months ago if that time line helps in pinning down a Lion update. PLEASE HELP!!!

Unfortunately, the problem (for me anyway) was not actually connected to any software update or other program issues. I got my computer in August, 2011. It ran fine until the black screen issues began in Feb., 2012, or thereabouts. After a couple months, I finally called Apple (computer then under extended warranty). It took a couple calls and some digging, but the problem turned out to be an issue with the iMacs produced about the time I bought mine (so the phone guy said, anyway). Luckily, I didn't have to take the iMac to an Apple store. There was an authorized repair site in my town (perhaps in yours, as well, depending upon where you live). In the end, the repair person replaced the screen, the LED backlights, and some video controller (this was in late April). Since the repairs, I've had no problems with the screen or computer. Sadly, if your warranty is expired, the fix could be a pricey one, maybe more than the computer is worth. Still, you could get an estimate for the costs. Also, given that the issue is a known one, perhaps Apple might do something about the problem (slim chances, true, but perhaps worth the cost of a service call). Sorry I don't have more encouraging results (assuming your problem is the same as mine with the same causes).

I'm extremely unhappy with this issue. I have been a loyal Mac customer since 1992 when I bought my first mac. Since then I have purchased 6 macs. Not to mention Mac's I purchased when working for corporations and agencies. I have never experienced an issue like this. I purchased my 27" iMac December 29, 2011. It worked beautifully until late September 2011. I called an Apple specialist in mid Noverber when the black screen started to happen more often. We went through several tests over the phone after which he determined I needed to make an appointment at my nearest apple store location and take it in. I live about 30 minutes from an apple store. I took my iMac into the Willow Bend store in Dallas on December 12. They had it for 5 days. They said it was fixed after they replaced the video card. After waiting 5 days for a compuer I work on daily and need for client work. When I returned home on the fifth day, the computer had been on for maybe an hour when it happened again. I hoped it was a fluke. 3 days passed and it seemed to be ok. Yesterday, I could not go 15 minutes without it blacking out on me. It is incredibally frustration especially since I am very behind on client work now due to this issue and could actually miss out on additional client work or loose a client all together because I'm unable to get my work done.

I did discover a key command that will allow me to get the login screen back. Sometimes I can't even login before the screen goes black during login. All the while music is continuing to play and my files are fine.

The key command is controll,shift,eject all together then space bar by itself. Sometimes you have to hit the spacebar a couple of times before you can get to the login screen. I purchased an apple care extended warranty the minute this all started to become a real problem in November.

I am a loyal Apple customer, I love apple products. I just bought a generation 4 iPad with retina display but, I CAN NOT EXPRESS ENOUGH HOW UNHAPPY I AM THAT I HAVE TO LUG THIS BIG COMPUTER BACK TO THE APPLE STORE AGAIN TO BE REPAIRED! What a freaking hassle. Set an appointment, load it up take it down there talk with the "Geniuses". It all takes so much time that I do not have. Considering, that this is a "known problem", the only right and fair thing to do is either fix the problem correctly the first time or please just give me a new computer! It is serious that I get this problem fixed and fast!

Note that my screen went black 5 times while I was typing this.

Have you called Apple and asked if they can do a 'mail in repair' ? they will send a courier to collect it and ship it to an AASP for diagnosis and repair.

I have the same problem and have replied in various communities about this issue. I bought mine in July 2011 and started having the blackout issues just outside of the 1 year warranty. I can't tell you how upset I am to have spent $1700 on a new computer and I got 1 year's worth of use out of it. My screen blackout is getting worse and some days I just shut it down and walk away because it's so frustrating. I keep pushing the issue with Apple and am disappointed that they have not issued a recall. For a company that touts it's superiority to that of the PC, they are sure letting a lot of users down. I am a long time Mac user (back to 84) and supported this company during the early 90's when Apple almost went under. Now I have a problem and they can't step up to the plate and fix it. I have one last appointment at an Apple Store on Monday so I'll see how it goes.

IF YOU ARE HAVING THIS ISSUE, CALL APPLE CARE AND REPORT IT. THEY NEED TO KNOW THAT IT'S NOT AN ISOLATED INCIDENT. UNTIL ENOUGH PEOPLE COMPLAIN, IT WON'T GET RESOLVED THROUGH A RECALL.

It was shortly after the expiration of the one-year warranty on my mid 2011 iMac when the screen issue started (last December). I was able to work through it with reboots but eventually the machine became a brick. The genius bar replaced the led display for me for ~$500. The fix lasted for one day. I then bought a new SSD (I use a single SSD) and swapped that in to no use. I brought it back to the Apple store and they were most helpful, providing a free replacement of logic board and video card (a $1100 expense). That was a month ago and now the problem has surfaced again and my iMac is a brick again.

Since I got the machine back from the logic board replacement, I've been vigilantly watching the temperature of the internal components with the iStat dashboard app. Today, before I left for lunch, I noticed a temp of 70 degrees celsius on the Power Supply and a value close to that on the cpu and when I got back from lunch the machine was blacked out - it worked only once more today and now seems to be a brick again. That's the highest reading I've seen on the power supply in the month I've been warching. Would it make sense to try replacing the power supply? At this point though, some other components may be toast.

Hi, I hope you find this information useful:

A few years ago, we purchased iMac 27" 11,3 (Mid-2010) (with i7 2.93Ghz, ATI 5750 1GB VidRam, etc.) for our offices and software development team. They were originally shipped with Snow Leopard and worked as expected and without any problems. However, a year later, we upgraded to Lion and all of machines immediately exhibited the same problem: the screen would go to sleep by itself and would require a hard reboot or sleep on/off. (Only the screen was asleep and the rest of the iMac continued to function; this was confirmed by screen sharing to the machine.)

Due to the severity and impact on our business, we immediately contacted Apple and their genius bar staff in New York/SoHo. They were unable to determine the root cause, so they replaced all of the logic boards, video cards, and screens, and got us back online asap. This resolved the problem, but we were curious to know why. After days of rigorous testing, we concluded that the issue is caused by a bug in MacOS. Specifically, faulty Kext files (Kernel Extension files extend the functionality of the MacOS Kernel) for the ATI drivers. So, why did the replacing the hardware work? We think that the Kext files that were released and distributed with Lion (and later MacOS versions) correctly supported the newer hardware revision of the replacement components, but not the older ones.

If you're experiencing this problem, short of replacing the components or waiting (for another 3+ years) for Apple to hopefully fix their OS software, you can lessen the effects and be able to recover faster by doing the following: (Please bear in mind that these are not permanent fixes.)

1. Turn on "Hot Corners" and assign one corner to "Put Display To Sleep". When your screen goes to sleep, move your mouse (which still works) to that assigned screen corner for a second, then move it again. This will wake your screen. You may have to do this a couple of times, but it's much faster than a hard reboot or a sleep on/off for your iMac.
2. Turn the brightness of your screen to a low setting (10%-15% of the total brightness).
3. Turn on screen sharing, so you have a last resort method of accessing the machine.

If you're not convinced that it's a MacOS software problem, then do what we did and see for yourself; install Windows 7, Windows 8, or Linux via Bootcamp or as the only OS on the iMac. Those operating systems and drivers worked flawlessly for us; the bug does not occur and the screen does not go to sleep, but if you dual boot and switch back to MacOS, the bug reappears because the iMac is loading faulty Apple MacOS software.

Good luck!

Turns out Apple acknowledged a problem with the video card on some mid-2011 iMacs and mine was one of them. If your 2011 iMac is bricked, check the S/N with this article or contact apple. http://9to5mac.com/2013/08/16/apple-opens-graphics-card-replacement-program-for- some-mid-2011-imacs/