2011 27" iMac not booting

[kaintxu]

Hi all,

I have a 2011 iMac that has been playing dumb for a while. For the last year or so it has been rebooting out of nowhere when working, when the load bar completed it's course instead of taking me into the desktop it just reboots the iMac again and again, or I just get a white screen with nothing on it.

I have read about the issue before and done what they suggest but nothing helps. I formated the HD and made a fresh install, and on the same day it happened again.

Can I get any tips on why this might be happening, and is there any solution? Is this an HD issue or is it something else? I'm now posting from my work laptop as I've not been able to start the iMac for 2 days now.

I wanted to replace it by a new one, but with no 2018 iMac, I didn't want to pay the price for the 2017 one as it's almost 2 years old now and we are paying well outdated hardware as brand new, so any tips helping repair this so I can go ahead until something new comes out would be great.

Thanks a lot

 

[chscag]

Did you try checking the memory? Also, what happens when you boot the machine to safe mode (if you can get it into safe mode)? You can also try booting to recovery and run first aid from disk utility.

And, it helps us to help you if you tell us what you already tried so we don't suggest redundant solutions.

 

[kaintxu]

Well in the past I could restart in safe mode when getting the issue, but today, when trying to go into safe mode (holding shift down) I would just end with a permanent blank screen.

I've also tried with cmd+r into recovery mode and done first aid and found nothing.

Did the reset VRAM and all that and still nothing.

Any other idea? I have not tried checking the memory. What should I do, I have never had issues with it.

 

[chscag]

A good memory check app for Mac is Rember. And there is also MemTest86. There are other things that can cause your iMac to reboot like that: Power Supply or overheating. If the CPU fan was dead, the machine would quickly overheat causing a reboot. You can check that with an app that measures fan speed and temps. Your iMac has three fans.

I'm also wondering if the GPU is acting up? Hopefully you'll get more replies with some other ideas.

 

[AlaskaMoose]

I always have a startup hard drive or SSD, I can connect to the computer if I have to start it externally. In this case I can easily rule out the internal HD or the OS malfunctioning. I started doing this when replacing the Internal hard drive or SSDs as follows: cleaned and organized the internal hard drive using Disk Utilities, cloned it to an external hard drive or SSD, made it to a startup disk, and then replaced the internal with the external HD or SSD. The internal HD now became a backup drive for instances as the one you are experiencing now. By the way, when replacing hard drives, I also replace the CR-2032 coin-shape battery inside the Mac if it is a few years old.

 

[kaintxu]

I always have a startup hard drive or SSD, I can connect to the computer if I have to start it externally. In this case I can easily rule out the internal HD or the OS malfunctioning. I started doing this when replacing the Internal hard drive or SSDs as follows: cleaned and organized the internal hard drive using Disk Utilities, cloned it to an external hard drive or SSD, made it to a startup disk, and then replaced the internal with the external HD or SSD. The internal HD now became a backup drive for instances as the one you are experiencing now. By the way, when replacing hard drives, I also replace the CR-2032 coin-shape battery inside the Mac if it is a few years old.

The thing is how I create a bootable HD when its actually quite hard to manage to have it on. Any link? remember its a 2011 model, not sure it can easily reboot from USB.

I have managed to turn it on somehow, I think it decided to let me have a look at it, but not sure how long it will last.

I'm going to check this apps @chscag mentioned right now.

 

[Kfamily]

This exact thing just happened to my 2011 27” iMac this afternoon. It won’t boot in safe mode either, and in recovery mode it can’t repair the hard drive so I assume it’s corrupted. It says it’s unmounted and won’t mount it. I’m taking it to the apple store tomorrow since I’m not interested in fixing it myself. Just wish they had an iMac updated within sometime in the last 12 months; I would just buy a new one today.

 

[chscag]

Make sure you call ahead before going to the Apple Store genius bar. I believe your 2011 iMac is considered vintage as of Jan 31st which means Apple won't look at it after then. Get a quick appointment.

 

[Kfamily]

Make sure you call ahead before going to the Apple Store genius bar. I believe your 2011 iMac is considered vintage as of Jan 31st which means Apple won't look at it after then. Get a quick appointment.

Super helpful thank you! I couldn’t get an appointment through the app for a week, but I called and they said to come in an open tomorrow and a walk in appointment shouldn’t take long. Just in the nick of time! Thanks!

 

[Kfamily]

Make sure you call ahead before going to the Apple Store genius bar. I believe your 2011 iMac is considered vintage as of Jan 31st which means Apple won't look at it after then. Get a quick appointment.

Thanks again for the reply. My arrival 15 minutes before the store opened worked like a charm, and once they opened I was immediately helped. It is already considered obsolete technically, but they did do a free diagnostic and confirmed the hard drive died. They offered to replace it with the same 2TB part as my original for about $200 parts and labor and in 3-5 days. For sometime who isn’t inclined to do this myself, I’m happy with the price and service and will likely get some nice extra life out of this 2011 iMac. And then can patiently await a new upgrade. All in all the service experience was exceptional.

One thing that was interesting though was that to get my original corrupted drive returned to me rather than recycled, I had to pay another $80 or so. I opted to do this since my backups are not super recent and I’m not 100% sure all my recent stuff is safely in iCloud. Hopefully I won’t have to mess with recovering data from it, but I wanted to have that option just in case. Just seems odd to charge me extra for me to keep the original failed drive.

 

[chscag]

Yeah, I would have thought that your original drive be returned to you. I see no reason why Apple would want to keep it since you paid for the labor and the new drive. Doesn't sound right to me that you were charged $80 to get back your defective drive. Several years ago I had a hard drive replaced in an iMac by Apple but the machine was covered under Apple Care. They kept the old drive which is understandable since it was a warranty repair.

I would contact the store manager and ask to have your $80 refunded to you. Nothing to lose by trying.

 

[briloronmacrumo]

FYI/FWIW: GPU failures are common in the 2011 iMacs. My GPU and hard drive failed simultaneously. Good luck.