I know this might sound stupid and all, but how do you know when your mobo FSB is running at 1600Mhz?

Reason im asking is because i got some new DDR3 ram at 1600MHZ and i would like them to run at their full potential.

i have overclocked my cpu to 3.8 using 1333mhz ram.

Is there a setting i need to adjust, or is it done automatically according to the overclocking you have done to the cpu?