27" iMac (mid 2011), Continual boot loop, white screen, instability. No disk issues, Deep Diagnostic reports no faults

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Level 1

8 points

27" iMac (mid 2011), Continual boot loop, white screen, instability. No disk issues, Deep Diagnostic reports no faults

Hi. I've been having ongoing issues with my iMac (El Capitan) for some time.

All was ok with it apart from I had a list of planned clean up tasks and peripheral item updates to consider as well as an os software upgrade. It was a while ago now and i've followed so many online guides to rectify the problems that I can't recall what exactly happed to start the issues.

I think I was trying to link a small wireless camera to the iMac to transfer the images off it. I was attempting this wirelessly when the machine crashed. I attempted to restart and was greeted with the apple boot loop.

Since this I have followed various guides and attempted the following with varying degrees of success. SMC, NVRAM, PRAM resets. I've run recovery and run disk utility and detected no issues with my HD, i've run diagnostics in both quick and deep modes and found no faults. I've also booted into safe mode and accessed and run the machine.

Whilst doing all this the machine has repeatedly crashed or reverted to the boot loop and white screen issue. I took it into my local apple genius bar and they couldn't even access the machine fully to evaluate the problem completely.

I was advised by the genius bar to attempt a USB bootable start up to see if it was an issue with my start up disk and if the iMac behaved then this was probably the reason, if not then it was most likely a video processor issue.

Up until this point I hadn't been unable to back up my system but fortunately I managed to get the iMac stable enough to carry out full time machine back ups. Also at this point I used Etrecheck to check my system and realised my HD was almost full and I only had 4GB RAM. I was eventually able to clear out nearly 200GB from my 1TB drive and double my RAM (which apparently still isn't enough?)

After a more resets, white screens, restarts and eventually getting into safe mode I was able to follow some Etrecheck guidance and deleted dubious start up and launch agent files.

It seemed that things were stabilising and I was seemingly able to start attempting to use the mac again but then the system crashed again. That's where i currently am.

It would be easier to ascertain issues if I could just boot into safe mode immediately however this isn't the case and I have to make repeated efforts before it randomly works.

If after all this it is a video processor issue then the only 'home' fix for this i've seen is the rather laborious baking of the video card. It seems a common problem with iMacs of this age and model.

Any help appreciated. I can post the last Etrecheck reports if necessary.

Thanks in advance.

iMac 27", OS X 10.11

Posted on Feb 26, 2020 3:22 PM

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Answer 1

QuickPost

Level 10

103,437 points

Feb 26, 2020 3:54 PM in response to kieran-__

Hello,

At this point it sounds like you have performed all of the troubleshooting steps we could provide. You may need to reinstall macOS.

How to reinstall macOS from macOS Recovery - Apple Support

Trying doing what is called an archive and install. Follow the steps to reinstall macOS from Recovery. Do not erase your startup disk. This essentially just installs a new System folder on your startup disk while keeping your data intact.

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Answer 2

rkaufmann87

Level 10

148,494 points

Feb 29, 2020 10:39 AM in response to kieran-__

What I see is you have a 2011 with a problematic GPU, the report also indicates the machine is suffering from Kernel Panics. KPs are difficult to troubleshoot but my money is on the GPU failing. That GPU had a repair program some years ago that ended a long time ago so this is why I am thinking the GPU is failing.

Please post your last KP report and we can look to see if it's software related. If it were my computer, I'd quite wasting time on it and replace it, it's 10 years old and cannot run current versions of Mac OS. I have a 2011 27" too however mine is running ok but I intend to replace it in a couple of months.

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Answer 3

HWTech

Level 9

69,464 points

Mar 1, 2020 10:31 AM in response to kieran-__

I agree with @rkaufmann87 about replacing the GPU. You will have no idea if the GPU you receive is any good or how long it will last. If you do purchase a GPU make sure it is from a reputable source with a good return policy.

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Answer 4

HWTech

Level 9

69,464 points

Feb 26, 2020 7:40 PM in response to kieran-__

If you post the latest EtreCheck report we can provide our opinions on it.

To check the health of the hard drive run DriveDX and post the report here using the "Additional Text" icon which looks like a piece of paper. If you have a Fusion Drive, then post the report for each drive.

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Answer 5

kieran-__ Author

Level 1

8 points

Mar 1, 2020 3:57 AM in response to HWTech

Hi. I have removed the app cleaner apps that remained and searched for the kernel panic reports. However they or it appear to have been removed this morning - "removed expired problem report 31.1.2020". I did search this out previously and the last kernel panic report was linked to the Soundflower audio app which I have since removed.

I will attempt to follow your instruction regarding DriveDX and memtest86 but this may take sometime depending on my work schedule and the stability of the iMac.

@rkaufmann87 - Whilst attempting to solve my issues, I had become aware of the issues with 2011 GPU's. If it indeed ends up being this problem I may have to consider getting it fixed (if possible) whilst saving for a whole new mac system.

I'll aim to get drivedx and RAM tests completed and report back.

Thanks again for the help.

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Answer 6

rkaufmann87

Level 10

148,494 points

Mar 1, 2020 9:36 AM in response to kieran-__

If it does appear to be the GPU, you very likely won't be able to find one as they have not been made for years. At that point it does not make sense to spend any money on a 10+ year old computer. It makes sense to spend the money replacing it.

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Answer 7

kieran-__ Author

Level 1

8 points

Feb 29, 2020 10:27 AM in response to HWTech

EtreCheck - Report generated: 2020-02-29 17:43:36

Hi I've managed to get the iMac up and running in order to get a new Etrecheck report. I thought i'd do this before attempting to re-install or recover the OS.

Thanks

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Answer 8

HWTech

Level 9

69,464 points

Feb 29, 2020 1:08 PM in response to kieran-__

I still see an AppCleaner in the report.

If you are going to perform a clean install, then you should first check the health of your hard drive. To check the health of the hard drive run DriveDX and post the report here using the "Additional Text" icon which looks like a piece of paper. I would be happy to review the DriveDX report to assess the health of the drive.

Since you do have extra memory installed in this computer I would suggest running a memory diagnostic. You can create a bootable Memtest86 USB drive using Etcher. Option Boot the USB drive and select the orange icon labeled "EFI".

@rkaufmann87 is correct that some of the 2011 iMacs did have faulty GPUs. Seeing the full Kernel Panic report might be useful in trying to determine the cause. Post multiple Kernel Panic reports if they are available. You can access the Kernel Panics by launching the Console app located in the "/Applications/Utilities" folder. The panic reports will be located within one of the "Diagnostic" folders or in "/var/log" or "/private/var/log". The file name will begin with "kernel" and end in ".panic". The date & time will be contained within the name as well.

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