Calculating FSB:RAM 1:1 ratio. which numbers to take?

run cpuz a href="http://www.cpuid.com/cpuz.php" rel="nofollow"http://www.cpuid.com/cpuz.php/a it will tell you your your actual fsb and much more ive been using it for years to optimize my pc's if your running 6400 in duel channel then your fsb should be 200. and your memory at 400 mhz