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What is wrong with my iMac?

1

1000

macrumors member
Original poster
Mar 20, 2010
87
24
Hi all.

My iMac died a week ago. It starts up fine, gets to the grey screen with the Apple logo, thinks for a bit and then the Apple logo disappears and stays on the grey screen forever.

I know a little about the mac, so I tried the following:

1. Reset the EPROM.
Didn't help, same symptoms

2. Booted in safe mode
Booted to the Apple Logo, then the loading bar started filling, completed the load and then i just got the grey screen, waited 10 mins, nothing

3. Swapped out the RAM
Swapped the SIMS in the machine, tried different combinations, different slots, didn't help

4. Tried booting from the Mountain Lion USB installer
Tried booting from the USB installer, allowed me to get to the boot options, loaded up the USB key for a minute or two, then just froze on the grey screen again.

All this makes me think that the HDD is the component that has failed, seems to WANT to boot but never gets there.

Is there anything else I can try before I ebay it for parts ? It was stolen a year or two ago and spent 2 weeks in some drug addict's car boot before the cops found it and I got it back .. so I thought maybe GPU/CPU might have been knocked about, but it seems to want to boot and goes through all the motions during boot, right up until the stage I think it seeks the HDD.

Any thoughts on anything else to try ?

1000
 
Turn it off and press the power button. As soon as you hear the startup chime, press and hold command-v until you see a bunch of white text on a black screen. What lines does it get stuck on or repeat endlessly?
 
Thanks for the suggestions guys, will try both today !!

1000
 
First port of call should be to run the apple hardware test! That will tell you if it's a hardware issue or not
 
Sounds like the problems I had with my Mac mini. It went for the odd crash to constant crash to grey screen. After trying everything you tried and more I took it apart and the hard drive connector was falling out
 
Hardware test won't run. Using Control -V, the bootup runs fine, finishes and then grey screens. Can't see any recognisable errors other than a warning that the wireless is not connect, nothing else stands out.

My money is on the HDD. I think I could probably repair it myself, or swap it out.. I've seen it done and it's not that hard.

1000
 
Last edited:
1000 said:
Hardware test won't run. Using Control -V, the bootup runs fine, finishes and then grey screens. Can't see any recognisable errors other than a warning that the wireless is not connect, nothing else stands out.

My money is on the HDD. I think I could probably repair it myself, or swap it out.. I've seen it done and it's not that hard.

1000
Click to expand...

If you do go this route, I'd put an SSD in the iMac and make it fly.

Might as well make it worth your time for all the work you have to do.
 
This is why one keeps a bootable clone external drive around.

If you had that (instead of the USB drive with the installer app on it), you could hook up the external drive and attempt a "nomal boot up" that way.

If the iMac -still- failed to boot, there's a good chance that what's wrong is not due to a "drive problem", but something else inside.

I've had a case similar to yours -- that is, my Mac would start to boot, display the Apple logo and "spinning gear" as the OS loaded, and then..... nothing, just a gray screen.

I booted externally from my backup clone (see above), deleted the "finder plist" prefs file, and then restarted. All was back to normal.
 
Can I make a bootable clone with the imac in TDM ? I guess I'd be making a clone of what could be a HDD image with at wont boot anyway so might be a waste of time ?

1000
 
1000 said:
Hardware test won't run. Using Control -V, the bootup runs fine, finishes and then grey screens. Can't see any recognisable errors other than a warning that the wireless is not connect, nothing else stands out.

My money is on the HDD. I think I could probably repair it myself, or swap it out.. I've seen it done and it's not that hard.

1000
Click to expand...

It is command-v. Based on what happened, you didn't actually boot into verbose mode.
 
p3ntyne said:
It is command-v. Based on what happened, you didn't actually boot into verbose mode.
Click to expand...

The verbose mode parsed all the start up stuff, then once it was complete it returned to the grey screen. I didn't see any glaring errors at all.

1000
 
My '27 iMac, mid-2011 had the exact same symptoms when the video card died. If you happen to have the Radeon 6970 Apple has a replacement program and any retailer will replace it for free.
 
Typically if it fails to boot from an external source (the install disk, for example) then the internal hard drive is not the problem. There are rare circumstances in which the hard drive (or more likely the connector) hangs up the SATA bus (like the exampe with the connector being loose) but the hard drive itself is not likely the source of your problem.
 
jaxhunter said:
Typically if it fails to boot from an external source (the install disk, for example) then the internal hard drive is not the problem. There are rare circumstances in which the hard drive (or more likely the connector) hangs up the SATA bus (like the exampe with the connector being loose) but the hard drive itself is not likely the source of your problem.
Click to expand...

Stripped it down and replaced the HDD, same problem. If my imac was just the standard build from 2012, would it have the 6970 in it therefore I can get it repaired free ? I can't remeber what GPU it had !!!

1000
 
The 2012 iMacs switched to nVidia cards and had them integrated onto the logic boards. The 2011s have the ATI Radeon 6XXX cards installed on duaghtercards attached to the logic board. Also, the 6970 was the top-tier card for that series, with the 6770 being bottom end for the 27" and the 6570 being bottom end for the 21.5". The 2012s also had thin edges and the glass was part of the display assembly and not separate from it.

I would say that it might be a good idea at this point to take it in for diagnosis, preferrably at an Apple Store because they will most likely not charge for the diagnosis.
 
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