Sick iMac won't complete boot (it's not the HD)

Try using 1 ram chip at a time, and than try them in different slots. Also see if it lets you do the Apple Hardware test. http://support.apple.com/kb/HT1883

If you do not have the original install disk look up the specific AHT test and try to download it off a torrent.

 

Will it boot in Target Disk Mode, and do you have another computer with FireWire you can plug it in to?

 

Apple Hardware Test is not a fancy GUI like other things your have tried to run, so do not discount it so easily. Messing with kernel extensions wont do anything, since it has the same issue with any type of boot media.

 

No solution but same problem

My mac has developed an issue that sounds very like yours. Won't boot or takes forever too boot. Prior it had been increasingly showing the spinning beach ball of death.

It could boot in recovery mood and eventually erased hard drive and reinstalled Mountain Lion and then recovered all my files/settings from TimeCapsule.

However the start up issue is still there intermittently.

 

I've certainly heard about people experiencing RAM-related problems that manifested after their Mac was up and running. By any chance do you still have the original RAM around to try? When I replace memory, I try to keep the original sticks around for situations like this. (4+ years is a long time, I know.)

 

I'd try booting a Linux live distribution from a USB stick just to see if the system can boot it. Linux is a great hardware test in itself; if Linux boots without problems, your hardware problem is working fine and it's just OS X that causes the problem.

If you have a working system, download Ubuntu 12.04 LTS from ubuntu.com, put it on a USB stick (the documentation for that is on the website), press the Alt/Option key on your "sick" Mac and boot from the stick.

Booting Linux from a USB stick takes a while. But if end up seeing a graphical desktop environment, you know that your Mac basically is okay.

If you see a bunch of kernel errors, you will at least get a hint at what might be wrong with your system.

Those messages are just informational and don't suggest that anything's wrong. Even the "link down/Reason 1 (unspecified)" message is absolutely normal at this stage. Because, well, at this stage during the boot process the Airport link -is- still down.

The problem lies in whatever happens -after- OS X has initialized the network cards and what is -not- shown in the logfile.

I would not remove the internal drive and use a different computer to install OS X on it. Make a clean installation directly on this computer and install the OS onto the internal hard disk. Either use the DVD that came with the computer or use a retail version of OS X for this - do NOT use an OS X DVD that came with a different Mac. But I think that any retail or AppStore version of OS X Snow Leopard or later should work just fine on that Mac.

Actually, no. I'd rather expect a "gray screen of death" somewhere during the boot process, to be honest.

Either try booting Linux from a USB stick - they all have good memory tests on board - or even try booting into a Windows installer. The Windows installer also is a good memory test; when you run into a blue screen or similar strange behavior while booting a Windows DVD, you know that your memory is the problem. (That's because the Windows installation, unlike Unixes, loads a lot of stuff into high memory areas that are not immediately used by Unixes at this stage. So Windows usually crashes earlier which in this case is a good thing because it is a better indication for memory issues.)

 

I posted this on the Mac Pro board, my Mac Pro is in the shop for the third time since April with the same three random issues at boot up.

They are:

1. It will boot to the gray screen and with horizontal lines scrolling down the screen and go no farther

2. It will boot to a gray screen and I will never see even the Apple logo and go no farther

3. It will boot to the desktop and all seems well except for the message that the bluetooth track pad is not recognized ( track pad cursor will not move either)

In all three cases the only solution is a hard shutdown via the on off switch. The next boot in all cases will be normal.

Six month old MacPro running Lion. It has been in the shop for over two weeks this time, and was in for at least two weeks each of the other two times. Remember it was brand new in April of this year.

They have not been able to duplicate the error although they have noticed some irregular entries on the control log.

As background: My wife has a two year old Imac that has been flawless, and the Imac we bought our Daughter and son ibn law almost three years ago has also been trouble free as are our MBP

I had a MacPro for two years that was in the shop constantly for various hardware problems and finally the good people at Apple took it back and replaced it with this new one that is now in for the third time. I will be the first to admit that software issues are hard to correct especially if they are random.

Needless to say I have lost faith in the Mac Pro and would jump at an Imac if they offered. I am losing too too much work time.

Good luck with your problem

 

I have a 24" imac also and appear to be having the same issues. Hangs at the spinning cursor, can boot into single user mode, that's it. For a few times I was able to boot off the boot CD and run the apple hardware test but then that just stopped working also (won't boot off of any CDs/drives/etc).

After reading a bunch of posts my best guess at this point is that it is a gpu failure (8800). I was having some gpu like graphics symptoms for a short time before the machine completely stopped booting. From what I've read, sometimes a gpu failure will prevent the machine from booting in this way (though I don't have any links offhand). Apparently the 8800s were prone to failure, unfortunately it's past the 3 year apple care and there is no official recall or anything.

 

"I gotta say, they do a pretty decent job on repairs. I dont remember what fixing the imac cost me, but they'll fix EVERYTHING thats wrong on a laptop for $280 flat fee. I had a logic board replaced, they gave me a new battery, new optical drive"

Regarding the "flat fee fix" option -- did they offer that to you, or did you have to request it?

Just wondering -- which Apple store did you take it to? (state)
Considering the problem, the cost was reasonable. With a hardware problem like that, you weren't going to be able to resolve it by yourself....