We continue coverage of an issue where the lower (or less frequently, upper) memory slots in some PowerBooks fail, leaving users with less available RAM than is actually installed. As previously noted, some users are not aware of the issue until they check the "About This Mac" pane accessible via the Apple menu or experience significant slow-down in a particular application.
It now appears that there are two causes, and two very different solutions to most cases of this issue.
In one case, the RAM is simply seated improperly. Removing the module, and re-installing it, making sure the connection is tight, has resulted in the previously disabled module working again for several readers.
MacFixIt reader David Schloss, for instance, writes:
"After reading your posts on the failing RAM in some PowerBook models, I checked my 'About This Mac' and found that my PowerBook 15" 1.25 GHz was showing 1GB instead of 2GB of RAM available. I don't have the test CD handy so I powered it down, took out the upper DIMM and tried to power it up. I got the 'error' noise associated with bad RAM. I flipped the same DIMM to the upper slot and it booted. I then powered down, and put the DIMM back into the lower slot, same issue. Took it out and re-seated it and this time it started up fine. I put back in the second DIMM and the Mac sees both. I'll keep running it until I get to a copy of the test CD, and I'll email my results."
In the second case, the PowerBook's logic board is faulty, and must be replaced. Most users whose machines are still under warranty have reported success in seeking repairs from Apple.
Swapping RAM modules A handful of users have been able to successfully work around this issue by simply switching the the location of their RAM modules (module in upper slot moved to lower slot and vice versa).
MacFixIt reader Davis Chapman writes:
"We have a Titanium PowerBook G4 17-inch 1 GHz which just got back from the shop with a RAM slot failure. At first the machine would periodically crash. Then we noticed that sometimes it reported only 256 MB in the second slot rather than 512 MB. Switching the third party ram into the primary slot worsened the problem and we finally need the logic board replaced as well as both RAM modules. Thank goodness we had AppleCare which took care of the logic board and Apple's RAM module."
Another reader, James Franklin writes:
"I just received my 15" Rev B PowerBook back from repair a couple days ago for just this problem. RAM installed in the lower slot just disappeared. Fix was to replace the main logic board. Even though my Powerbook was out of warranty (by 3 weeks), Apple fixed it at no charge."
Unfortunately, other readers are having difficulty obtaining service from Apple, with technical support representatives blaming the problem on "bad RAM" --- which may be a causal factor in some instances of this issue, but not all.
One reader having difficulty getting repairs, Jurgen Proschinger, writes:
"Now that my RAM has disappeared and I?ve identified the error you reported using Apple's Hardware Test that came on the installation CD (Apple Care staff recommended ?reinstalling the system,? as usual, which I did of course, not) I?m stuck with the working RAM in the upper slot. When asking Apple here in Germany how long it would take to fix my 15 month-old Powerbook G4 15?? (thanks God I have Apple Care!) they told me that repairs would take a ?minimum of three weeks.? And before that I?m not entitled to get a replacement from Apple. Renting an iBook from a retailer would set me back some EUR 500,- for three weeks, and it?s difficult to find a shop here in Germany that does rent Apple product at all.
"So, for the time being I'm continuing to work with a faulty logic board and less RAM... needless to say, I'm not amused by Apple's customer service nor their response to the problem ('clearly that?s resulting from bad RAM, did you purchase original Apple RAM?')."
Our previous coverage of this issue, in November 2004, revealed a confirmation from one authorized Apple service provider who wrote "I can confirm this issue as I have seen it several times and have had to send units to Apple for this. In some cases the RAM slot fails after a period of initial use and in other cases the slot fails immediately."
Now we've received word from another authorized Apple service provider who provides unconfirmed information about Apple's memory slot testing at the factory:
"My information is that Apple only test the top slot in production to save time. They populate the top slot on the assembly line and if that works, they assume the other slot is OK. False economy. "
Also problematic is the fact that some users are having their logic boards replaced only to have them fail again a few months later.
For instance, MacFixIt reader Jordi writes:
"The same problem occurred with my PowerBooks Aluminum 1.5 Ghz 2004. This is the second time that I've had the problem. They changed my original logic board and the new one had a failed lower RAM slot three months later."
MacFixit reader Hasani Hunter writes:
"I was getting the same problem, with the lower slot no longer being recognized, so I called Apple Support and they suggested that I swap the memory sticks, which I did.. and now everything works fine.. Maybe the act of re-seating the sticks actually fixed the problem (I doubt that it is a permanent one though)."
If you are experiencing a similar problem, please let us know.Resources