G4 won't accept new memory

hello -

have inherited 2 powermac g4 450 mhz agp machines use @ non-profit arts organization run. believe these either "sawtooth" configuration ( http://www.lowendmac.com/ppc/g4saw.shtml ) or "mystic" configuration ( http://www.lowendmac.com/ppc/g4mp.html ), former.

each came 2 128 mb dimms (256 mb ram each), anemic of course, bought 2 dimms of 512 mb ram of same type, intending add 1 each machine. same bus speed (133 mhz) , voltage configuration (contact edge indents) existing memory. there 4 dimm slots.

dimms go slot fine, not recognized system. boots if aren't there; there no abnormal boot beeps or flashing power button. doesn't count them existing in ram pool (per "about mac").

did try both dimms themselves, separately in first slot , in first two, , boots failed warning beep, flashing power button, , no video.

can take these vendor (a trusted local whitebox shop) , have them test them, there special need besides pc133 sdram?

noticed these new 512mbs 16-chip dimms, , existing 128mbs 8-chip dimms. matter? vaguely recall there's difference between 16-chip , 8-chip.

thanks!

 

macs tend pickier ram other computers. did buy generic pc ram or did buy "mac compatible" ram?

(intel-based macs don't seem affected, still stuff)

 

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