@Matt_H
I think my A1 is old enough to have the chip
I have an A1-XE (7455 @ 933MHz) which I ordered on 1st November 2002, and received on 4th July 2003. I was told that the on-board sound wasn't working, and had to buy an SB128 card.
I've just had a look at the board and I don't have the sound chip. It looks like the earlier boards with 800MHz G4s probably have the sound chip fitted.
