Oscilators... hang on just spamed a post about this?

LOL

as Harrison states the 28.8 is infact the governing Clock of the A1200, most of the chips internally devide this state so in effect they are running at 14.4, although not all the chips. the 020 on the other hand has to consult to these chips and as such is bound by the governing clock of 28.8/2 (14.4) unless you run it in NTSC which has the custom chips running slightly faster.

When you add fast Ram the 020 when doing its own work doens't have to wait for access to chip ram and as such can run at the FULL governing clock speed of the card (if it has a clock) or its internal factor of the governing clock in this case its around twice as fast.

however it will slow down with the more Chip access it does,