2008-2009 iMac endless boot loop and vertical lines

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122 points

2008-2009 iMac endless boot loop and vertical lines

My dad has an iMac from 2008-2009 and it's been fine.

However yesterday it suddenly developed vertical lines on screen (shown below). These lines appear to be 'above' the Apple logo. Sadly I can't access the computer info

The Mac is locked into an endless boot loop where it never gets beyond the Apple logo and loading spinning circle.

I have booted using option key and tried the Recovery partition for startup. This again goes to the Apple logo and the grey spinning circle until it says 'If you want to continue in English hit the return key' which I do and then nothing (the circle stops spinning). Same happens when booting into Safe Mode.

I have also tried to boot from his recovery (separate USB) drive and nothing... Fortunately I can access his backups from this so he still has his data.

I have also tried Target mode via Firewire from my laptop and the iMac hard drive doesn't mount (although the Firewire icon displays on the iMac screen).

I've also tried re-setting the PRMA and SMC.

My guess is this is a motherboard failure somewhere as it seems beyond the normal graphic card type issue. For some reason my local store is not doing Genius Appointments at the moment so can't take it in.

Is the consensus this is one dead iMac?? Thanks 🙂

(Note the 'smudges' on screen are from my phone, not on the iMac!)

Posted on Feb 9, 2016 4:04 AM

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Answer 1

Best reply

BleverCastard

Level 1

53 points

Feb 18, 2016 1:42 AM in response to Steve Hayes1

Hi Steve Hayes1,

I had one come in the other week with these lines - GPU Issue. Got it replaced and worked like a charm.

As for the endless loop, Try booting from an external drive and loading an OS. Does it still do the endless loop?

Regards,

BleverCastard.

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Answer 2

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 4:36 AM in response to BleverCastard

Thanks for the help and input BC, glad you got the iMac fixed !

Sadly, this iMac won't boot from the Backup drive.

When I try to boot via holding down C and the install DVD, the screen suddenly wipes from top to bottom with a darker shade of grey.

Then the screen pops up with the message saying I need to re-start the Mac.

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Answer 3

Feb 9, 2016 4:39 AM in response to Steve Hayes1

Hi Steve Hayes1,

Seems like you have a hardware issue(may not just reside to the GPU!).

When you boot - Hold ALT. What happens then?

Regards,

BC.

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Answer 4

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 4:42 AM in response to BleverCastard

Thanks again, yes I've tried this sadly!

Basically the three bootable options appear - of the Macintosh HD, the Recovery Partition and the external Backup drive - and then the same as above - nothing or into the re-boot loop if select Macintosh HD etc!

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Answer 5

Feb 9, 2016 4:43 AM in response to Steve Hayes1

So it won't even let you boot into RM to re-install the OS?

- BC

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Answer 6

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 4:45 AM in response to BleverCastard

No unfortunately - it won't load the OS at all it seems - cannot get past the initial Apple logo and spinning circle via normal boot, OSX DVD, Backup drive or Recovery Partition! Strange that seems to have happened at the same time as the GPU issue...

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Answer 7

Feb 9, 2016 4:48 AM in response to Steve Hayes1

If you have a thumb drive or a spare drive laying around, load OS onto it, plug it into the machine and try and boot from it.

Let me know what happens. I have a feeling your drive is on the very edge of failing.

- BleverCastard.

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Answer 8

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 4:59 AM in response to BleverCastard

Thanks again so much BC... tried boot from USB memory stick running Mavericks - got to the 'to continue in English hit the return key'... and then nothing (same as with the internal Recovery Partition).

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Answer 9

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 8:27 AM in response to Steve Hayes1

OK so the latest update...

Managed to connect the iMac to my MacBook Pro via Target Mode and could see all of the Macintosh HD contents etc.

I ran Disk Utility on the iMac Macintosh HD from my MBP and no problems reported.

I then booted up the iMac in Single User Mode and ran fsck with no problems - message saying Macintosh HD appeared OK.

Then tried to boot up normally and went through the start up loop once again...

Anyone have any other ideas?

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Answer 10

Feb 9, 2016 8:37 AM in response to Steve Hayes1

Hi Steve,

connect it to your MBP and get the important data off of it and then reinstall OS on it

Regards,

BC

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Answer 11

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 8:48 AM in response to BleverCastard

Again, thanks for your time BC.

Just managed to boot into Verbose mode (Cmd-V) and watched the list of commands. The iMac hung as it reached a certain command line (shown below, had to grab an old camera so not the best and hard to see with the graphics card). Looking at it, I wonder if it's hanging as it tries to load up the graphics.

I will wait and see if any other ideas (if anyone can read / understand the bottom line of code). Otherwise will attempt a re-install of sorts via Target Mode as this is the only way I can access the iMac.

Thanks again 🙂

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Answer 12

Steve Hayes1 Author

Level 1

122 points

Feb 9, 2016 11:46 AM in response to Steve Hayes1

The error message appearing at the bottom of the screen I've tracked down to say:

AppleYukon2: Marvel Yukon Gigabit Adapter 88E8055 Singleport Copper SA

AppleYukon2: RxRingSize <= 1024, TxRingSize 256. RXMAXLE 1024, TXMAXLE 768, STMAXLE 3328

I've seen a few other posts about this. Someone says it may be ethernet-related. Haven't seen a definite explanation or fix for this. (e.g. https://discussions.apple.com/thread/2792362?tstart=0)

Am posting just in case this helps someone else in the future - or if I find a solution! (Most likely at the moment is a new iMac)

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Answer 13

Steve Hayes1 Author

Level 1

122 points

Feb 10, 2016 2:28 AM in response to Steve Hayes1

OK, so I tried the instructions in the discussions thread (above) to no success.

On re-booting in Verbose mode, I also see a bunch of SMC read errors - have reset SMC three times with no help. Pics of both here...

Is anyone able to confirm... Can I definitely do a Target Mode "install" onto the iMac because I'm running El Capitan on my MBP and the iMac is running Snow Leopard ?

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Answer 14

Feb 10, 2016 2:33 AM in response to Steve Hayes1

You can target disk mode Snow Leopard as well as El Capitan. So I couldn't see why you not.

Give it a try and let me know how it goes.

- BC.

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Answer 15

Steve Hayes1 Author

Level 1

122 points

Feb 10, 2016 5:36 AM in response to BleverCastard

Thanks BC,

Connected up by Target Mode, used a USB stick with Mavericks install plugged into MBP and then re-started MBP holding option key > chose the Mavericks install option > Installed onto the iMac via target mode ... and sadly was greeted by the endless boot loop. However, I could log in to the iMac from the MBP before disconnecting target mode. So presumably something somewhere (hardware) is doing something to halt boot on the iMac - so doesn't seem to be a hard drive issue?

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