Troubling iMac

A few months ago I bought a shiny 20" iMac. While the initial impression was good, I was not happy after the trouble I had installing Leopard and certain incompatibilities it brought.

Just when it seemed things were settling down I've got the system just dying on me after opening a large (120MB) PDF file. The screen turned black and then the system rebooted spontaneously. Another computer was on at the same time and it did not experience any problem, so I do not think that was because of a power spike.

Today, when I started the system there was a multilingual message in a centered dark square telling me to press the power button for several seconds to shutdown the system (neither the keyboard or the mouse worked). I have never seen that image before (but I failed to take a photo), it contained the message in Japanse too. It happens to be an OS X kernel panic.

When I powered on the system again I heard the welcome sound and next two beeps and then three beeps that repeated over and over again. It did not sound good. A quick check on the net (using other computer, of course) showed that 2 or 3 beeps signal RAM memory trouble (mine is the original RAM that came with the system and because of the cool and compact format of iMac is not user serviceable).

I removed the computer power cord for some seconds and then I connected it back to try again: No changes, same sequence of sounds; no joy.

Having nothing to lose I removed the power cord again and I applied some of my frustration through my hands (i.e. more than gentle taps to the system). After reconnecting the power the system booted up as normal. My guess is that the RAM is not properly seated on the socket. I'll be paying attention to see if something weird happens again.

Now I'm going to hunt for some memory test software.

Update: Thanks to Jesus coments (and this page) I realized I was wrong: My iMac does have two memory slots that are easily accessible by the user by removing two screws on the bottom part of the screen. Not sure the trouble was caused by memory though, as several diagnostic attempts gave no indication of memory faults. Anyway, if the problem happens again now I know I can access the system's RAM memory.


Hiroshi Ikeda said…
This seems related to a hardware problem, maybe memory, maybe hard disk. Anyway give a try to the Apple Hardware Test (it's in one of the systems cd, boot with the cd on the iMac pressing the C key or the Alt key).
Good luck.
Miguel Sánchez said…
Thanks a lot.

I'll try this out.

I do not think I'm buying another Mac anytime soon though.
Jesus said…
Hello Miguel:

What a bad luck!!!

Try the hardware test...

It sounds a memory problem....

Miguel Sánchez said…
When I made my buying decision I was a bit frighten of buying a computer with no user serviceable parts.

Now my worst fears seem to have become true.

Re-sitting (or replacing) RAM memory takes 5 minutes and no skills on another computer, but opening an iMac is a bit of a challenge (I do not have the suction cap yet) and it voids your guarantee.

It is said that good judgment comes from bad judgment :-)
Jesus said…
Hello again:

To reseat (o replace) the computer memory, you must only work in two screws...It is no necessary to open all the computer...The screws are located under the screen...

If you want to open the new imac then it is no easy and (as you tell), you need the suction cap to remove the main screen glass...

Miguel Sánchez said…
Unfortunately the only RAM in my iMac is the factory-installed 1GB SODIMM located inside the guts. The extension socket in the bottom of the screen is easy to access but empty at the moment.

Anyway, after discovering diagnostics on OS X 10.4 install disk are obtained by pressing D key, the system seems quite happy about the memory. Both the long and the short memory test agree that memory is now working properly.

I'll keep my fingers crossed (and maybe I'll look for that suction cap once the guarantee period is over :-)

Thank you for all your help.
Jesus said…
Hello Again:

Are you sure of that?

I was looking for how to change the RAM slots in your computer and I found this from Apple web site

You can see that your computer has 2 slots

It seems (but I am not sure) that you have an empty slot and a slot with 1 GB of RAM.

Please check this, because if you read the Apple document carefully, it talks about how to change your RAM or HOW TO REPLACE IT

I think that all the RAM is user serviceable (but not the graphic card)

Miguel Sánchez said…
You are absolutely right. All system RAM is user accessible. I did not know that because I never opened the memory cover before. Somehow I assumed that like a laptop the memory it comes with was inside the "difficult" area.

I have updated my post accordingly too.

Thanks a lot for the help,

Jesus said…
Hello again:

I'm glad to hear that...

In fact, in my Mac (an Imac Late 2006), two screws must be unscrewed. In your Mac, it is necessary to unscrew only a screw

About, the laptops...Apple laptops have the same system several years ago...

As far as I know, now the only Apple computer with memory no serviceable is the MacMini...I have a Mini, and I bought with 2 Gb of RAM (not from Apple, because is too expensive ) to avoid any opening problem.

If you want to open your Mac, check this:

Jesus said…
Hi again:

I forgot it :) , the new Macbook air has also a non serviceable memory

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