Old iMac hangs on grey screen at startup.

[Levina]

This is about my dear old iMac, late 2006. Some six weeks ago I replaced the hard drive (you can read about that here: https://forums.macrumors.com/showthread.php?p=20855101#post20855101) and all was really well. Performed like a charm.

Then, yesterday, it wouldn't wake up from sleep. I rebooted and after a normal start-up, it hangs at a grey screen.
I found Apple's instruction manual on what to do in case of a grey screen, tried all (peripherals, cables, pram and the other abbreviation thingy, checked RAM, etc.) but to no avail.

It will only boot in Safe Mode now. Anything else I throw at it, and it won't start up, like:
- original Tiger install cd: starts up, then hangs on blue screen
- an external (and healthy) Hard Drive, connected with a sata to usb adapter: hangs at Apple logo with spinning ball.

Much to my surprise I was able to do a Hardware Test (so cmnd+D worked), but all was well.
When in Safe Mode, Disk Utility says the hard drive is all right.

So, I'm thinking, this is not Hard Drive related at all.

Any suggestions? Is it kaput? Beyond repair?

 

[Levina]

154 views but no replies. Does that mean my iMac is beyond repair? Snifff...

 

[Bomb Bloke]

Apple's hardware test and Disk Utility tools aren't much good at picking up hardware faults. I wouldn't rule out anything just because those gave the "all clear".

When you say it "hangs at a grey screen", is there anything on this screen, or is it simply solid grey?

How did you "check the RAM"?

The external drive you tried, is this the one you were talking about in the other thread, set up as it was at the time (ie when this computer was previously able to boot of it)? What OS is on that, and what OS does the system usually boot to?

I'm leaning towards a RAM issue; probably that built into the graphics card. Not entirely easy to fix if that's the case, but it's too early to say.

While in safe mode, it may well be worth checking /Library/Logs/DiagnosticReports to see if anything's being generated in between your failed boots.

 

[Significant1]

Apple hardware test doesn't really test hardware, which requires drivers. Therefore my graphics card would go through without problem, however when starting osx it would crash as soon as driver was loaded and hardware acceleration was startet..

Not easy to guess the root of your problem from here...

 

[Mrmullad]

Grey screen

i had the same problem the thing I found out was to connect wired keyboard so I could boot into recovery.
Not sure if this is the same problem you have .
Hope it helps Dell

 

[Fishrrman]

The fact that it's booting into safe mode -- that is, that it is still capable of booting at all -- seems suggest that you have an OS problem, rather than a hardware problem (I could be wrong).

But when I read postings like yours, all I can do is sigh.
Because....

..... IF you had maintained a FULLY BOOTABLE external backup drive (created with either CarbonCopyCloner or SuperDuper), it would be a trivially simple matter to connect the backup and try booting from the external drive.

By doing this -- and if you got "a good boot" from the external -- you could ascertain that the iMac's hardware was ok, but there was a problem with the internal drive. Could be an OS problem (software), could be a drive problem (hardware).
But you would KNOW that the iMac itself was still ok.

I recall having solved the "grey screen" problem some years ago, where the OS would seem to load ok up to a certain point, and "hang" on a gray screen and go no further.
My solution: I booted from my backup, deleted the "finder prefs" file on the internal drive, and after that the Mac booted right up again.

Suggestion:
You also have a Mac Pro?
With a firewire port?
Then try this:
- See if you can get the iMac going into "firewire target disk mode"
- Connect the iMac to the MacPro
- If that works, can you mount the iMac's internal drive on the Mac Pro?
- If so, go into your home folder on the iMac drive, and try deleting the finder prefs, energy saver prefs, sleep prefs (if there are any), etc.
- Then separate the machines and try a reboot of the iMac.

Just something to try, no promises...

 

[Levina]

Yay, replies!! Thanks guys. Much appreciate the help.

@ Bomb Bloke:
I checked RAM by removing the Kingston strips and putting in the original ones. Made no difference.

@ Fishrrman, the problem is that it won't boot from an external drive. True, I don't have a bootable clone, but that's because there's nothing on the iMac that is valuable. All my work is on my Mac Pro and I have three back-ups for that, including one bootable clone.

So I simply made a bootable external drive using the Mac Pro, but the iMac won't boot with it - it starts up normally, the Apple logo appears and the spinning ball and then it just hangs there, ball spinning.
With the Tiger install cd the iMac starts up normally and then hangs at the blue screen (instead of the grey screen), so that doesn't work either (even though cmnd D does start the AHT).

I'm excited to try the firewire target disk mode though! However, the iMac is FW 400 and the Mac Pro FW 800 so I will need an adapter cable. I'll check my cables, but I'm pretty sure I don't have one. I can buy one for 8 euro and that's okay. I just have to wait a few days before I can try this.

 

[Levina]

Okay, so I connected the stubborn iMac to the Mac Pro, Target Disk Mode worked, I deleted some preference files, but that made no difference. Then, again in TDM, I ran Disk Warrior. It found what I think was small directory stuff, repaired it, but that made no difference either. I can come to no other conclusion than that the iMac has run its course.

So I think I will just retire the iMac and buy a 2012 Mac Mini to replace it. There's an Apple Reseller that's selling them new for 489 euro. Seems like a better option than the 2014 version with its soldered RAM (who on earth came up with that ridiculous idea?!).

Thanks again, everyone, and Fishrrman especially, for your help.