Lower RAM slot in some PowerBook G4 (Aluminum) units fails (#3)

We've been covering an issue where some readers with Aluminum PowerBook G4 computers have reported that the lower of the PowerBook's two RAM slots is no longer recognizing RAM. Numerous MacFixIt readers have confirmed this issue -- many of them not realizing they were "missing" RAM until our coverage spurred them to check their own PowerBooks. For example, Ben Boswell writes:

"Just checked my 1.5 GHz Aluminum PowerBook, and sure enough the lower 512[MB RAM [chip] has disappeared. I ordered this PowerBook with the single 512 installed and added the other 512 myself, which appears to be still working. Bought the PowerBook in June so still in warranty. Thanks for this heads up, otherwise would have probably gone unnoticed."

Douglass Feeney experienced the same problem in the past and, as noted by other users, the solution was a motherboard replacement:

"I had the lower slot in my 1.5 GHz Aluminum go about 3 months after receiving it. It took Apple almost 3 weeks to repair. I was told they were out of replacement parts (motherboard). Not my favorite experience with an Apple product that is used as a hub to a business. I'm now considering redundancy..."

What's especially odd about these "failed RAM slot" problems is that unless you don't have additional RAM installed (in which case your computer will appear to have no RAM at all) or you notice that your computer is running with less RAM than expected (via slow performance, etc.), there appears to be no indication of a failure. As Justin Pakes notes, Apple's Hardware Test won't even reveal the problem:

"We have one older Powerbook 12" 867MHz machine ? this is the early model that has the initial RAM soldered to the board, and one expansion slot. To cut a long story short, the onboard (soldered) RAM seems to have failed. Of course, we can't just throw a new piece of RAM in to test, but the machine will only register the RAM in the expansion slot, and removing the expansion slot RAM and the machine will fail to boot as expected. The part that threw us for a loop though was that this machine will still pass every one of Apple's Hardware Test runs, quickcheck or detailed."

Using the Apple Menu's About This Mac item or the System Profiler utility appears to be the best way to determine if your PowerBook is experiencing this problem.

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