"Just wondering why Mac modules won't work? The old PowerMac G4 has the same megarray connector, as far as I remember, and a Sonnet encore dual 1.8Ghz G4 is $250 cheaper than the single 1.7Ghz above while a 1Ghz G4 is $200. Surely that makes more sense for A1 owners who absolutely must have a new CPU."
The socket is the same but they are wired different so they will not work in an A1.
