I'm attempting to bump the RAM in a friend's 600MHz G3 iBook to acceptable levels for OSX and have run into something of an annoying issue. I'm using junk-bin parts, but it should be able to take PC100 and anything up to 512MB. Except both of the larger sticks I've tried--one 128MB PC100 pulled from an iMac that worked last week, and one 256MB PC133--haven't been recognized. Interestingly, OS9 actually gives an error about "failed memory test" on startup (then boots without the stick showing up). OSX appears to just ignore it--the install discs I've tried stall partway through the boot process, which is a symptom I've seen when trying to install OSX with only 128MB. (I'd expect it to either boot properly or panic if it was ok or recognized and bad.) Oddly, I've tried two 32MB pulls from iMacs, and both work fine. I've tried the obvious (reset PMU, PRAM, NVRAM), and while it's possible that I just have two coincidentally bad sticks in my hand, it's seeming like it's got some odd motherboard issue where it hates anything large. Is there something obvious to try that I'm overlooking here?