i have pc133 ram in my g4 along with pc100 ram
as long as the other spec is right then it should work fine
i cant remember right now whether the g4 takes edo or sd ram or what but if you get the right sort and right voltage then pc133 will work
and you can keep it for when apple up the speed of the ram with newer models ie when the g5 comes out with a faster ram bus
hope this helps
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