It's your RAM, to fry

A few months ago, I decided to resurrect one of my first Macs ever, the very computer that once held my life, to go. Unfortunately, not being invested with divine powers, I ran into a bit of odd trouble in the process. With the help of a friend, the solution soon became clear: here is to hoping it can help you too…

For a long time, the machine had run Mac OS 9 and Mac OS X without problem. Certainly, an iBook G3 (Late 2001) at 500 MHz shipping with 256 MB of RAM didn't exactly scream under Tiger, but it performed its duty reliably and never once complained of the load. Its hard drive is as robust as it ever was and the casing has not wrinkled in the least. However, the Apple-installed 128 MB SO-DIMM had been swapped with a Dane-Elec 512 MB SO-DIMM with no ill effects a while ago.

After a bit of shelf storage, I thought it best to clean-install Mac OS X, giving the machine a good test in the process. Unfortunately, this was not to be. While applications on the old system worked perfectly, no installer ever wanted to work, whether from the CD or Software Update. The error? A "codec overrun," which was more reminiscent of Hawaiian shirts, 3D penguins and QuickTime than anything else.

At this point, while I was busy tearing out fistfuls of my hair after hours of chanting and troubleshooting, my hardware and UNIX guru rightly pointed out the iBook was now working with one PC-133 RAM module — the added one — and one PC-100, soldered to the mother board. Theoretically, he added, it should work given he had been mixing PC-133 and PC-100 with no ill effect on similar machines running Mac OS 9. Still, it was a possibility…

For kicks, he decided to swap the added stick with another 128 MB PC-100 one he had lying around. Much to my surprise, this solved the problem. Was the mix causing our trouble or was the 512 stick faulty in some delightfully arcane way? Who knows…

Conclusions? Many! (As Dr. Bronner could phrase it.) No sign of RAM failure were ever apparent until an installer or updater was run. All applications, including rather intensive media applications — OK, intensive for the machine —, were behaving properly and never once did the system throw an error or a panic.

Mac OS 9 installed flawlessly as well and ran quite happily on what it thought was a high-end CPU — hey, it hasn't kept up with the times. Indeed, everything but the Mac OS X updaters worked.

As a software person, I tend to ignore the hardware side of things. Until my Mac starts beeping in scary patterns and displaying the sad Mac forbidden sign, I just assume the error lurks somewhere between the Cocoa and the puffs. Turns out I was wrong!