IMac G5 Random Shutdown

Posted on 2010-09-02
Medium Priority
Last Modified: 2012-05-10
I am working on an IMac G5 that has been randomly shutting down.  Somtimes it will run for a few hours, other times it will run for a few seconds and then just shut down like it has lost power.

I had replaced the PSU in the system a few months back and it was working good then, but now its back and im just not sure what is up with it.

Any ideas will help and thanks ahead of time
Question by:david1986
LVL 28

Expert Comment

ID: 33588439
You might try resetting the SMU:


In the above link is also a link to how to reset the PRAM.
LVL 12

Expert Comment

ID: 33588508
Check in /var/log/system.log (you can access this in Console as well).

You might find that the system is overheating and so automatically shutting down. This happened to my son's iMac G5 (without a camera). They extended warranty repairs on this model for some time due to issues with capacitors.



Author Comment

ID: 33589648
I tried resetting the SMU and still the same problem.  Unfortunately i have been unable to get the system to fully boot so i can not check the log file to see what info is in there.

If it were an overheating issue, would the system shut down that fast.  It is now shutting down about 5 seconds after the power button is hit.  

Any more ideas would be great.
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LVL 28

Expert Comment

ID: 33589893
I would try plugging it into another outlet or new surge strip in another outlet to make sure that it's not a power line issue.

Also possible that if there is a fan on the CPU, not sure if there is or not, it could be failing and it can take almost no time at all before a CPU will over heat.

Other than that, I would suggest another P/S.
LVL 28

Expert Comment

ID: 33589915
Not sure if this is your exact model, but here's some info on getting into the case and once there you could probably see the fan.
LVL 32

Expert Comment

ID: 33592192
>If it were an overheating issue, would the system shut down that fast.  It is now shutting down about 5 seconds after the power button is hit.  

If it's pre-warmed by prior power-on cycles, then yes.  Common problem with cracked thermal paste between heat sinks and CPU and graphic chips. I've seen it in notebooks...let it sit overnight and it will boot & run for a minute or two, then shut down.  After that, it won't get far enough to even start booting.

Accepted Solution

kpliew1 earned 1500 total points
ID: 33659044
Still is power supply problem, check your iMac still under "Repair Warranty" or not? Basically, it come with 3 months repair warranty.

Author Closing Comment

ID: 33802393
We still haven't gotten this straightened out. Just need to try another power supply I guess.

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