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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > Help! Problem with iMac 27" 2011

Help! Problem with iMac 27" 2011
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foo2
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Dec 25, 2014, 07:50 PM
 
Help! I'm having a problem with my trusty iMac 27" mid-2011 i7/3.4 Sandybridge.
  1. When I boot up with either SSD (Thunderbolt) or 1TB HDD (internal) the iMac will get to 30% on the bar, then restart. Sometimes it won't restart but will stay, stuck, on a completely gray screen
  2. When I boot up with the USB 10.10.1 Yosemite Install stick, I get a gray screen

Sometimes the iMac will simply freeze, screen turning gray (on both iMac 27" screen and external screen) and the only recourse is to turn the machine off.

Sometimes (when I Option-Cmd-PR and when I pull the plug for 20 minutes then plug it in and wait 1 minute, then power up) the machine boots perfectly and will be fine for a few days.

Help! I bought this on 10/15/2011 with AppleCare, but I think I'm just 2 months out of AppleCare. Sigh. Short of a new logic board, what do people do?
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Dec 25, 2014, 07:58 PM
 
Beliefs:
1. Because the problems are either exactly the same or very, very close to the same whether I'm booting from SSD, HDD, or USB stick, I believe the problem is hardware, not software.
2. The SMC seems to be the problem, not the PRAM. Resetting PRAM on its' own does nothing, resetting the SMC controller seems to "fix" the problem for the short (2 days? Sometimes just a few hours...) term. SMC Details: Intel-based Macs: Resetting the System Management Controller (SMC) - Apple Support
3. There was a graphics card recall, and my serial number is one of those that could be impacted. I have seen the green and white (blue and white? I forget) graphics once or twice lately, in the last week, although I didn't think to take a snapshot of it. Apple Initiates Graphic Card Replacement Program for Mid-2011 27-inch iMac - Mac Rumors

Help appreciated!
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
P
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Dec 25, 2014, 10:06 PM
 
I agree that it is hardware. First thing to check is usually the RAM - try booting with one stick only and see if that helps, and try switching to the other stick. Have you run the hardware test?
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
reader50
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Dec 25, 2014, 10:11 PM
 
I'd suspect the power supply. When you let the components cool off for 20 minutes, they will sometimes boot up successfully.

I would take it to the genius bar, mention the GPU glitches you've seen, mention the erratic booting, and mention the just-expired AppleCare. I haven't had to use AppleCare myself, but I've heard of cases where they waived a repair when it was just outside the coverage window.

Note that a bad GPU can sometimes prevent bootup. So it's entirely possible the graphics recall is your entire issue.

Edit: just saw P's reply. Yes, check the RAM first.
     
foo2  (op)
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Dec 25, 2014, 10:41 PM
 
Originally Posted by P View Post
I agree that it is hardware. First thing to check is usually the RAM - try booting with one stick only and see if that helps, and try switching to the other stick. Have you run the hardware test?
Good question. When I tried hitting D at bootup (I have a pre-2013 iMac) I got nothing but a gray screen (no bar on screen at all). Now that I can boot I will try booting with "D" again.
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Dec 26, 2014, 10:01 AM
 
Sigh. This morning the power was disconnected from the iMac all night, but when I reattached power it still wouldn't boot. /Frustrated
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
badcowboy
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Dec 26, 2014, 05:09 PM
 
Try a command-v when booting up to go into verbose mode. When I took mine to the genius bar, it was able to start in that mode (didn't take long for it to lock up again - I was able to completely back up the system by booting into 'safe' mode).

If it is the video card, that would be covered under the separate repair program - you shouldn't need an active applecare (hopefully).

My iMac 2011 just was in the store and got its video card replaced (I almost suspect that Yosemite uses more graphic resources than the previous version).

The one thing to remember is to remove any installed components you may have had installed. I had to go pick mine up and remove an internal SSD that I had put in before they would replace the video card. Not a lot of fun when the apple store is in the middle of the mall.
     
foo2  (op)
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Dec 26, 2014, 06:33 PM
 
I can't boot it at all now - even after Cmd-Opt-PR, after leaving power disconnected for the evening.... it will boot to 30% of the bar (safe mode, SSD, HDD, 10.10.1 install USB stick, etc.) and then it will reboot (and will then keep doing this forever). Sometimes it won't even get that far but just hangs at the gray screen.

Hitting "D" on the keyboard before or after the startup bong does not bring up Apple Diagnostics, ever.

iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Dec 26, 2014, 06:35 PM
 
Appointment set up for 8PM at Apple Genius bar - let's see if Apple's Geniuses can help!
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Dec 27, 2014, 11:24 PM
 
Just got the iMac back from the Genius bar. They were able to run diagnostics, and as a result were able to tell me that my RAM is bad. I'm going to wait a bit for the problems to come back, and then I'm going to swap out the RAM and see which is / which are the bad chips. Thanks Apple!
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Dec 29, 2014, 09:45 PM
 
Originally Posted by foo2 View Post
Just got the iMac back from the Genius bar. They were able to run diagnostics, and as a result were able to tell me that my RAM is bad. I'm going to wait a bit for the problems to come back, and then I'm going to swap out the RAM and see which is / which are the bad chips. Thanks Apple!
Tried RAM in pairs and singly (top slot only, nearest the display). None of the RAM chips behave differently - the bootup sequence quits in exactly the same spot every time.

It's starting to look like Apple's discovery that a RAM swap fixed things was a fluke brought on simply by powering off the unit, removing the power cable, and doing a SMC reset.

Still frustrated and unsure what to do... seems very unlikely all RAM would have failed and all RAM would cause the startup to fail in the same place (freeze at 30% of progress bar).

I'm downloading 10.9 to build another bootable USB stick, just on the (silly) idea something different might happen.

/Frustrated....

** Clarification: I've rotated and tried singly all four of the chips that were in the machine, and I've tried a 2GB stick (a new one) and been able to reproduce the problem exactly. In other words, new RAM didn't help - it seems Apple's diagnosis was wrong. I've made another appointment at the Genius bar today at 1:30.
( Last edited by foo2; Dec 30, 2014 at 09:30 AM. Reason: Clarification on RAM used)
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
foo2  (op)
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Jan 8, 2015, 12:28 AM
 
After several days at the Apple Store during Trip-To-Store-v2.0, Apple replaced the 6970M graphics card gratis, and I've now got a fully working iMac 27" 2011 again!
iMac 3.3/i5 (2015) 24GB 2TB 10.13.1
MBP 15/2.5 (2014) 16GB 500GB 10.13.1
MBP 15/2.3 (2012) 16GB 250GB 10.13.1
MB 13/2.4 (2010) 9GB 120GB 10.13.1
MB 13/2.0 (E-2009) 4GB 120GB 10.13
     
   
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