Earlier this week, I consulted a client whose 5-year-old iMac was constantly locking up due to a kernel panic. Prior to my appointment, she had taken the machine into the Apple Store a couple of times for diagnostic repair. Apple’s tech staff replaced the original 512 mb RAM chip in memory slot #1 and said they couldn’t replicate the error after keeping the machine on for several days. After trying a number of standard troubleshooting procedures, I figured out why the kernel panics were taking place.
The iMac has plenty of remaining disk space. Only about 20% of the 250 gig hard drive is being occupied by data.
Repairing Disk Permissions while starting the computer in Safe Mode didn’t accomplish anything. On the other hand, running Activity Monitor at the same time I was opening and closing applications helped me determine the cause of the problem. The iMac kernel-panicked the moment when there was no more of the installed (not virtual) memory available. My client and I watched the kernel panic unfold as I opened each new program and kept an eye on remaining memory until iPhoto pushed it over the edge.
To remedy the situation, I advised my client to order a 1 gig RAM card that I will install in memory slot #2 at a later date.