2011 iMac odd graphic corruption

[Lahmy88]

Saw that Apple’s Safe Mode Support page mentions:

Safe mode in OS X Leopard v10.5 or later also disables accelerated graphics.

So, gave it a go and no glitches appeared whilst running it. Rebooted and so far haven’t seen it return. Will update if I do.

 

[Lahmy88]

Rebooted and so far haven’t seen it return. Will update if I do.

And sure enough it was back after a couple of hours or so
Prior to safe mode though it was particular severe so at the very least it’s helped slightly

 

[mbritto.fr]

I had the same issue you guys had 18 months ago and it got so bad sometimes the glitches started during the startup when the screen was still gray.
I saw a youtube video of a guy recommending to cook the graphic card in the oven (for real). He said the graphic card was desoldered and the heat would fix it. I was about to throw my iMac away so I tried it. The longer was to access the graphic card and take it out, then 8min in the oven and I put it back in the iMac.
it worked! For the last 18 months the iMac was working...then it started back.
I will probably use it as an external screen now but it would maybe work again with the oven hack. You can find many YouTube videos of guys telling you how to do it. If this is the same problem I had it may work for you but it could also “cook” your graphic card so try it as your last resort
good luck

 

[DJR5985]

I know this is an old thread but I wanted to chime in here. I have a mid 2011 21.5" iMac with the AMD 6750 M running Sierra 10.12.6 and have been dealing with this issue for over 2 years (upon transitioning from mountain lion to Sierra.) I did have a power supply slowly die in this machine that I replaced with a pull from a working iMac, and that fixed the power issue but the pixelation and glitches started after upgrading to Sierra and seemed to be un-related to the power supply.

This issue has slowly gotten worse over time. I have never been higher than 10.12.6 because my audio software is only compatible with this OS so I'm at an impasse. I have spent the last week trying to diagnose and figure it out. As with the above posters, the computer runs flawlessly in safe mode and the internal Mac hardware tests come back reporting the GPU as "ok." I have tried a clean install of Sierra on a separate partition of the HD but that still produces graphic glitches. 3-4 days ago, the computer had gotten so bad it was unable to even boot into the desktop without locking and crashing.

After removing some larger files from the internal HD and doing some general cleanup, doing some first aid on the partitions I started looking for software issues, particularly things that may have been causing kernel panics. As of today, I've gotten the computer to actually run on my normal Desktop (not safe mode) and that only occurred after disabling some startup processes and/or LaunchDaemons and going through the kexts looking for issues. I've gotten the computer back to a more intermittent graphic issue where I'm typing this on it in Safari at the moment with no issues.

For previous or future posters that may read this, I'm wondering out of curiosity if any of ya'll have (or had) Adobe products on your machines? Specifically the CreativeCloud and any graphics programs (photoshop, indesign, acrobat) because I'm starting to suspect those are at very least contributing to the problem. Disabling most of the adobe background services and removing a couple adobe cache/plist files as seemed to improve things which makes me curious. I have multiple AdobeCRDaemons that run no matter what I do and a kerneltask process is often using up a ton of memory (I have 16GB) without anything Adobe even open (so not sure what that's about.) At very least, Adobe is a resource hog and drives me crazy. I make an attempt to quit all those processes when I start the computer. My next step will to be completely removing ALL adobe software and any remnants to see if that has any impact followed by a total system wipe to factory default, and back to a fresh install of Sierra.

Like many of you my troubleshooting efforts seem to lead me to believe this is some kind of software related conflict, particularly because in Safe mode there is not a SINGLE trace of the pixelation or glitch issue whatsoever as highlighted in this thread. In the past I can also confirm that maximizing an app or safari window would temporarily solve the issue, but then that no longer worked. I also found that when things started to get really bad putting the computer to sleep and then re-waking it would fix the issues temporarily. Additionally, I find that when using Pro Tools (which is an insanely resource heavy audio recording program) with windows on two different screens and a lot of information flying around, the issue was barely present if at all (which is a head scratcher.) Based on information around the web about this AMD card it wouldn't surprise me that the issue is related directly to it and/or it's drivers, but it sure seems like manipulating things in the software realm has an impact on the problem. If I can't figure out a fix I guess it may just be time to put this thing to sleep permanently, but she's had a good run.

 

[Richdmoore]

I did not have any adobe products on my computer (when I still owned it.)

I was able to confirm temperature affected the condition on my computer (I put it in a dry but cold non-heated garage to test.)

Hopefully your issue is software and not hardware, but the temperature test pretty much confirmed mine was not. (The iMac was sold to gazelle for parts or them to fix.)

 

[DJR5985]

I did not have any adobe products on my computer (when I still owned it.)

I was able to confirm temperature affected the condition on my computer (I put it in a dry but cold non-heated garage to test.)

Hopefully your issue is software and not hardware, but the temperature test pretty much confirmed mine was not. (The iMac was sold to gazelle for parts or them to fix.)

Thanks for the reply. I am gonna try everything I can but at the end of the day, an upgrade is probably inevitable.

 

[mbritto.fr]

This is most definitely an hardware issue for me : the GPU has troubles when it is under too much load. The fact that it works in SafeMode doesn't rule out an hardware issue, because the Safe mode uses the graphics card at its minimum level. Some apps (Adobe in your case, or even newer macOS versions) may use more GPU intensive tasks and triggers some glitches.
Sometimes issues are pink vertical lines, other times they are graphical glitches. When they first appear they are rare, but the more you wait, the more they will appear until your imac becomes unusable.
I've had those issues twice : 18 months ago, I fixed them by following this guy's video :

I put the graphic card in the oven (for real)
It worked flawlessly...for 18 months.
Issues came back last month : cooked it again and it worked...again.
I'll see in 18 month if it comes back

 

[Bananaj]

What is being discussed here is NOT a hardware issue, I don’t know how many times people have to say this. I booted Lion on an external drive on my affected machine and it worked flawlessly.

I can’t easily go back to Sierra because I (unwittingly) waited too long and my Sierra-era backups were overwritten, so I would have to reinstall everything from scratch, a massive undertaking.

I reported the bug to Apple and they closed it as a duplicate, so they have acknowledged the bug but aren’t fixing it. They have effectively ruined perfectly usable hardware for thousands of users through defective software, most of whom will have thought it was a hardware issue and replaced the machine.

I understand that supporting legacy hardware is not something that they are willing to do but not supporting it and outright breaking it are two different things. I shouldn’t have to buy a new machine just because Apple strongly encouraged me to install an OS that was not fit for purpose, and I shouldn’t have to spend potentially weeks getting back up and running on a downgraded OS with a different file system because of their incompetence.

I was living with the issue despite occasionally losing work when the machine locked up but now that I have to work from home I am experiencing the issue more and more. It’s just pathetic from a company with Apple’s resources.

 

[mbritto.fr]

What is being discussed here is NOT a hardware issue, I don’t know how many times people have to say this. I booted Lion on an external drive on my affected machine and it worked flawlessly.

Just because your problem is software related (which is still up for debate), doesn't mean that "what is being discussed here" is for everyone. You are stating that, because you don't the issue on old software, means that the issue musts software related. This is a good assumption, but this is not a proof because of so many factors (different os, different drivers, etc.).
On the other hand we have people (me included) that managed to fix the issue one the same OS by doing stuff on the hardware only, without changing anything software related. For those people it was hardware related.

Good luck with fixing your mac, I really hope you will, but please keep an open mind and stay courteous with people sharing their experience trying to help you.

 

[Richdmoore]

What is being discussed here is NOT a hardware issue, I don’t know how many times people have to say this. I booted Lion on an external drive on my affected machine and it worked flawlessly.

I can’t easily go back to Sierra because I (unwittingly) waited too long and my Sierra-era backups were overwritten, so I would have to reinstall everything from scratch, a massive undertaking.

I reported the bug to Apple and they closed it as a duplicate, so they have acknowledged the bug but aren’t fixing it. They have effectively ruined perfectly usable hardware for thousands of users through defective software, most of whom will have thought it was a hardware issue and replaced the machine.

I understand that supporting legacy hardware is not something that they are willing to do but not supporting it and outright breaking it are two different things. I shouldn’t have to buy a new machine just because Apple strongly encouraged me to install an OS that was not fit for purpose, and I shouldn’t have to spend potentially weeks getting back up and running on a downgraded OS with a different file system because of their incompetence.

I was living with the issue despite occasionally losing work when the machine locked up but now that I have to work from home I am experiencing the issue more and more. It’s just pathetic from a company with Apple’s resources.

I can only offer my data point. My problem was immediate upon startup and 100% reproducible when I had the computer cold soaked to about freezing (left overnight in an unheated garage). When it was used in a normal room temperature conditions, the problem was somewhat intermittent, and never immediate upon startup.

The fact that temperature affected the frequency of the problem (always when the computer was cold, very intermittent normally) with no other changes points to a hardware fault, at least for my system.

 

[Michel007]

Relative old Thread, but still relevant: For the last couple of weeks experience same issues of increased clutter and increased 'freezing' of iMac. Glad I finally found this thread.
Any new insights in the mean time?
Have 2011 iMac, with AMD Radeon HD 6770M 512 MB.
Running High Sierra 10.13.6
txs