2011 iMac 27 graphics card problem?

I agree Climberfx, I have been through 2 HPs in the past 6 to 7 years. So i recently bought a used mac, late 2011 with the 1gb Radeon 6770M and 8GB of ram, from all the talk about how macs last so much longer and now im in the same boat!

To the point:

Im having similar problems except my mac will just shut down or when put to sleep and open up the lab top it just a black screen. After i try to boot back up i get a lime green boot up screen w horizontal white lines and after this abnormal apple boot up screen just goes to a grey screen and doesn't ever get to desktop. After several attempted reboots can get luck and will boot to desktop, but seems to be getting worse.

I have noticed that it crashes only when i have Microsoft power point and or word, and a web browser open with a few web pages. I also noticed that more and more ram gets used up. Even when i close out of these programs there is still more ram used then normal. 6gb compared to around 4 at normal desktop boot up.

Went to the Apple store and they want to replace the logic board for $310 at an assembly line. will take a week.

Mhunt, how is your mac holding up? Any problems since the new ram?

The problem has not returned for me. I'd love to hear if replacing RAM has helped anyone else or if I'm an outlier.

I was fighting with my iMac until last week, when the only thing i could try was installing Yosemite Developer update (now on number 4)

The Yosemite could manage better the machine, but the squares and locks on machine wouldn't stop, but minimize.

Observing the machine, i could see that it freeze more when cool then when in heavy use. Everyday i start to use it, it lock some times, even moving a window on screen, then, after some warm up, it turn into usable.

So, today i try something different and unusual.

I put a mp4 video (720p one, with around 150mb) into loop playback. so, the GPU never goes unused 100%. (never could down enough)

And it works. No more square dots, no more lock on, until now.

The thing i think is the problem, is a bad manufacture and a soldering problem, so, when it is cold, the parts retracts and this soldering get with contacts problem. But when it is hot, the things expand because, and then this bad soldering keep connected.

Until i have a new machine, and then i can put this one to recall/change to another new video board, this will solve my problem.

I hope that could help you all.

Cheers

I just wanted to update my own post. After several weeks, the artifacts returned. They were made even worse by the Yosemite upgrade. This board is filled with people having the same problems, same Radeon model (6770M) yet it seems like the real fix is a hardware one. I will not be spending that kind of money to fix this machine, at least not with Apple. More thermal paste? *****I have no idea.

<Edited by Host>

Same here. I also have the 6770M Radeon, and have been getting square artifacts every now and then. Was hoping that the Yosemite update would fix it but no luck.

I'm convinced now that apple has set the Fan vs Heat relationship in OS X incorrectly, and video cards are being damaged after 3-5 years of use.

I just had to replace mine... $450 worth of work.

I installed the SMCFanControl app and will now watch my GPU/CPU heat like a hawk.

- Rake

By chance is anyone using Firefox for your internet browser?

I'm having the exact same scenario, but it's also showing up running Windows 7 via Bootcamp. I've been running Mavericks since day 1, and haven't yet upgraded to Yosemite. However, I've recently begun using Firefox as my default browser in Windows and that's when the "color block" issues started. Windows must see the problem developing because it tries to unload the graphics driver then Blue Screen's me. It happened to me twice this morning, so I've been using Chrome ever since, and have had no issues.

It's very bizarre. If it happens with Chrome, I'll update my reply.

same iMac (27-inch, Mid 2011) same issue. AMD Radeon HD 6770M 512 MB video card is the problem according to the Apple store. Past warranty however they did offer a $150 fix- replacing the original Video card with the same thing. I figured I might upgrade the card to 1 GIG. Any advice brethren?

Same problem cropped up here. iMac 27", Mid 2011 with AMD Radeon HD 6770M 512 MB.

GPU hangs and can't restart... causes a cascade GPU failure and blank screen for me. It is NOT a temperature related problem. And other process can still be running, including sound and voice chat... you just can't see it! Occasionally will cause complete system crash. Very disappointing.

From system Log:

5/12/15 6:38:55.000 PM kernel[0]: Trying restart GPU ...

5/12/15 6:38:55.000 PM kernel[0]: [1:0:0] Failed to reset hung GPU! result=151 ulResetBlockBitmap=0x00000100 ulResetResultBitmap=0x00000100

5/12/15 6:38:59.000 PM kernel[0]: [1:0:0] GPU HangState 0x00000000, HangFlags 0x00000006: IndividualEngineHang 0, NonEngineBlockHang 1, FenceNotRetired 1, PerEngineReset 0, FullAsicReset 1

I am also having the same problem with the same machine Mac Intel 2011 mid, same video card why hasn't Apple realize this is a recall problem if all the same year same video card having the same issues. Class action law suit might help them fix this problem or the whole world could know how crappy they are building there product in order to get them out quicker to compete with PC that are working and cheaper to fix when they do have problems. Why pay triple for apple for less of a product.

Hi all,

I'm suffering exactly the same issues, running a 21.5-inch, medio 2011 iMAC, with... a AMD Radeon HD 6770M 512 MB ! The problem started about 1 year ago (August 2014), I believe after an update to OS X 10.9.4.

The scenario is alike as described in this post (and in similar post: Red and green square dots?):

- colored squares appear on the screen,

- with some bad luck it's like ' a waterfall', and the screen is full of them,

- if you're lucky: they disappear

- there is a much higher probability that they appear in iPhoto (which I use very frequently...)

- in 70 % of the cases, the system crashes completely: hanging ...

- no entry in logs is made

--> frustration guaranteed !!!

I brought my iMAC to an Apple repair-centre here in Belgium; they tested the machine for 1 week and could not find anything :-( also extensive HW-test didn't show anything.

Any help is welcomed...

Peter

I am also having the same problem with the same machine Mac Intel 2011 mid, same video card why hasn't Apple realize this is a recall problem if all the same year same video card having the same issues. Class action law suit might help them fix this problem or the whole world could know how crappy they are building there product in order to get them out quicker to compete with PC that are working and cheaper to fix when they do have problems. Why pay triple for apple for less of a

Maybe I have found a really simple solution to this problem: I have been experiencing the same problems for almost 6 months - since upgrading to Yosemite. The only thing that has helped (for a short while) has been, just as some other people have pointed out, to re-boot.
But about an hour ago I checked the settings (and since I see these in Swedish, I am guessing the English words): Apple symbol-> About this computer - Monitor (or Screen) -> Color.

Once there I changed the profile from "iMac" to "iMac calibrated" and the problem with the flashing squares went away instantly. The screen has been clean since one hour. The longest time in six months!
Will post again if the problem returns. Hopefully it will not.

I have gotten my problem with the screen fixed, I took it into the Apple store and they were able to tell me what the problem was. All it was that when I first upgraded to Yosemite it did not load correctly, so they uninstalled Yosemite back to Maverick then upgraded again to Yosemite it's been more than 2 months without any problem. Make sure you are using Time machine and back up all your files before doing this process, remember that any software problems, you can get fixed at the Apple store for free as long as it's thier product. Good luck God bless...

I wanted to follow up to this as I just picked up my 2011 iMac from the Apple Store. I finally had enough of the artifact issues I have been having off and on for a couple years now. There is clearly a problem with 6770m hardware but unfortunately, I couldn't get them to cover the repair since the official recall was for the 69XX models. The good news is that although I had to pay to fix it, they replaced the faulty hardware for $150 including labor! It was ready in 2 days and the process couldn't have been easier. The Genius diagnosed a bad video card within minutes and I was pleasantly surprised at the repair price ($112 for a new 6770 board.)

I tried hard to convince myself it was a software issue but sorry to say folks, these are balky models we have. Get it fixed for good and save yourself the stress! For the record, the "reduce transparency" setting allowed me to put things off as long as I did- that was the single most effective tweak that reduced the artifact problem.