Well, for whatever reason, Eyetech have declared 800MHz the 'rated' speed for the system as a whole.
It *would* be nice to know the degree of flexibility in the settings, and the reason for such an 'underclock.'
(My guess for a contributing factor would be that Moto's speed-binning probably works a bit different from, say, Intel's - despite any tricks Apple have pulled off, perhaps 933 is the highest it can go before it melts? There's also the question of heat dissipation off the Articia, which I remember was suspect a while back.)
