PC-133 is backward compatible with PC-100 RAM. Some Apple notebooks required low profile SO-DIMMS, but I don't know if the G3 Powerbook does. If your spares fit in the machine, they should work. Mel "It is almost impossible to remember how tragic a place the world is when one is playing golf." ~ Robert Lynd On Nov 27, 2003, at 9:47 AM, jchance at midsouth.rr.com wrote: > > > I have a G3 Powerbook that needs another stick of RAM. The original 256 > added when new does not stand up to Panther. I have 2 sticks that I > removed from one of my G4 Powerbooks. The G3 uses PC100 RAM. The > spares > that I have are PC133. Can it be substituted and what are the expected > results if it can. Both are SO-DIMMs. Thanks for anyone help.