iBook G3 Clamshell not recognizing new RAM modules

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Level 1

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iBook G3 Clamshell not recognizing new RAM modules

Hello everyone, I'm having a problem with an old iBook G3 Clamshell Tangerine. Since the installed RAM module wasn't working properly, I decided to replace it. I tried two different 128MB PC100 SD-RAM SO-DIMM modules, one from Siemens and the other from IBM. Neither is accepted; when I enter System Profile on OS 10.0.4, they're flagged as incompatible. The firmware is updated to version 4.17. After removing the RAM block, the Mac runs perfectly with the soldered-in memory, but it only has 64MB. Currently, it's running with two separate partitions, one with OS 9.2.2 and the other with OSX 10.0.4 (the last one booting with less RAM).

Is the RAM really incompatible? What am I doing wrong with the buying of this RAM blocks? Which one should I buy? I also tried to reset the NVRAm from Open Firmware, as well as I asked about the memory from OF, I can attach the result if needed

Thanks everyone, have a nice day.

Earlier Mac models

Posted on Aug 22, 2026 4:00 AM

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Answer 1

Top-ranking reply

PreCognition

Level 4

3,638 points

Aug 23, 2026 3:11 AM in response to Gabrielemac

PC100 itself isn’t the problem. Apple’s original iBook documentation says the memory bus runs at 66 MHz and that 100 MHz SDRAM parts can be used.

The catch is that these iBooks are picky about the SO-DIMM’s internal organization and SPD information. A generic 128 MB PC100 module can physically fit and still be reported as incompatible.

Since yours has 64 MB soldered on the logic board, Apple lists 320 MB as the maximum, so you can use a compatible 256 MB module. I’d look for one specifically sold and guaranteed for the iBook G3 Clamshell/PowerBook2,1, rather than buying another generic PC100 stick. It should be a 144-pin, 3.3V SDRAM SO-DIMM.

The fact that the iBook runs normally with the module removed also points more toward incompatible RAM than an NVRAM or firmware problem.

Apple’s original specifications are here: iBook - Technical Specifications - Apple Support

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Answer 2

Gabrielemac Author

Level 1

4 points

Aug 23, 2026 3:32 AM in response to PreCognition

Good morning and thanks for your reply. I wasn't very specific in my post, but the two RAM modules I tested were 144-pin, 3.3V SDRAM SO-DIMMs at 100MHz, so I don't really understand the incompatibility.

I'm looking for guaranteed modules for the iBook; I can't find many in Italy that aren't too expensive, although they'll be giving me another free module to try this week, this time 133MHz, again 144-pin, 3.3V SDRAM SO-DIMM.

I also thought the slot might be malfunctioning, but since it recognizes it, I don't think so.

I'll let you know how it goes; I hope I can find the right RAM. Thanks everyone.

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