User profile for user: _Dayley_
_Dayley_ Author
User level: Level 1
14 points

27" mid-2011 iMac restart on boot, after login or after waking up

Hi,


I had a mid-2011 27" iMac computer with 3.4 Ghz core i7, 8GB RAM, 1TB internal IDE hard drive standard from Apple. But the iMac after power-on would chime and then was stuck in a boot-loop. It would load to 60-75% on the loading bar below the Apple startup logo, then freeze for 10 seconds, and then restart. I have tried every possible start-up command on the keyboard you can imagine.


I added additional RAM cards and upgraded to 16GB, and also upgraded the hard drive to a 1TB SSD with a the additional heat sensor. Boot-loop still remained - although the load bar was a lot faster.


After looking further into it, all fingers on the internet were pointing to the graphics card on its way out. I searched high and low for a replacement graphics card, but found that financially it would outweigh the price of the actual Mac itself for a new card. I also looked at second-hand cards which didn't look too pleasing also. However, I found a seller of another mid-2011 27" iMac 3.4Ghz core i7 computer which worked out as the same price of a second-hand graphics card! Only his graphics card had been upgraded from the standard 512mb to a late 2012 1gb graphics card, which the listing stated the computer was fully working. So obviously I bought.


So, using the newly bought iMac, I installed my RAM cards to upgrade their 8GB to 16GB again, installed my SSD in the new machine and powered it up! - the load bar got to 100%.... and then restarted, then got to 100% again and allowed me to login. I logged in and all was good. - until I put the iMac in sleep mode. The iMac remains in sleep mode no problem, but after I wake it up, I login, and then sometimes it will cutoff and restart.


When it restarts it will load to 100%, then restart a second time, and then the second attempt seems to get to 100% again but allows me to login and begin using. While using it doesn't seem to cutoff or restart. It is only when I am starting up or waking it up!


Please note I have tried the following:

  • Re-installing Mac OS (despite it being a new SSD entirely from the original IDE HD)
  • Formatting and reinstalling again
  • Resetting NVRAM and the PRAM during startup
  • Switching the RAM cards
  • Changing the power cable
  • Trying different plug sockets
  • Relocating the iMac to a different home entirely incase it was a home socket issue
  • It is using an entirely different motherboard now from what I first had
  • It is using a completely different graphics card from the first encounter
  • All other components are from the second computer, so all different


I am really stuck for ideas! Can anyone else advise what this may be? And better still, how I could try and fix it!


iMac 27″, macOS 10.13

Posted on Oct 17, 2020 4:31 AM

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12 replies
User profile for user: BDAqua
BDAqua
User level: Level 10
250,259 points

Nov 16, 2020 11:18 AM in response to _Dayley_

Uninstall CleanMyMac per their directions , restart, then run etrecheck again to see what chaff it left...


On CMM…

https://discussions.apple.com/thread/251370955?answerId=252661013022#252661013022

https://discussions.apple.com/thread/251442443?answerId=252814053022#252814053022

https://discussions.apple.com/thread/251464557?answerId=252841819022#252841819022

https://discussions.apple.com/thread/251889446?answerId=253629452022#253629452022

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User profile for user: _Dayley_
_Dayley_ Author
User level: Level 1
14 points

Dec 5, 2020 3:22 PM in response to BDAqua

I have used 2 different iMac's motherboards remember. To have the exact same problem on both iMac's RAM slots would be a very strange coincidence.


Its now 10 days later since my last post, and my iMac is restarting 6-7 times, every time, upon wakeup! Some of the restarts are occurring before I type my password in during the loading bar process, some immediately after I type my password, and some up-to 3 minutes after.


I have also had restarts while my iMac was asleep. Around 4am while my computer was asleep and I was also, I heard the startup chime. So I got up and looked at the iMac, and it was restarting. It restarted 6 times during this episode.


I have noticed on some of the restarts there has now been the well-known 'popping noise' before it restarts.


I am extremely close to walking in to an Apple store and slamming the iMac on the shop floor as Apple have not assisted with any of the faults I have had with any of my Apple products from day one of my purchase, even during my Apple care period.

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User profile for user: BDAqua
BDAqua
User level: Level 10
250,259 points

Oct 17, 2020 8:36 AM in response to _Dayley_

Whew, good testing! :)


Safe Boot, (holding Shift key down at startup), does the problem occur in Safe Mode?


Safe mode attempts to repair Disks & clears lots of caches & loads safe Drivers, & prevents loading of 3rd party extensions, so if Safe Mode works try again in regular boot.


If that doesn't do it, we might find the problem with an etrecheck report.

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/


Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Whew, they've changed pastebin & made it harder, but after pasting in, click Create new paste button, then Embed button, then copy the URL...

<script src="https://pastebin.com/embed_js/KuvnghqA"></script>


The important part is...


https://pastebin.com/embed_js/KuvnghqA


Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

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User profile for user: BDAqua
BDAqua
User level: Level 10
250,259 points

Nov 17, 2020 1:38 PM in response to _Dayley_

Enable Full Drive Access to see more information in etrecheck.


Have you blown the dust out of the intakes lately?

What temperatures does this App report? Especially the GPU.

This App can be used to speed up the fans, all my iMacs would be dead without it.

Never ever ever drop fan speeds below the speed that the Mac itself is calling for.

MacFansControl…

https://www.crystalidea.com/macs-fan-contro

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User profile for user: _Dayley_
_Dayley_ Author
User level: Level 1
14 points

Dec 15, 2020 12:03 AM in response to _Dayley_

Okay another update:


Due to the vast amount of restarts, I have been trying to fiddle with it a little and found a temp solution:


If I go to the Apple logo > System Preferences > Energy Saving >

And move the slider for the two attributes: Computer Sleep & Display Sleep to: NEVER

and also untick the box: Put hard disks to sleep when possible


Then it doesn't restart, as my hard drive/computer does not sleep. After I have finished using, I just leave the computer for the weird but colourful screensaver to come on. Upon return I still type my password in, but no restart.


Note that if I put my computer in sleep mode like this, and then wake it up, it will still restart.

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27" mid-2011 iMac restart on boot, after login or after waking up

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