ya, quite wrong.
i always misunderstood that dual channel = ddr2, infact, ddrs
are able to have dual channel too.
The data flows during the older version of RAM (is it SDRAM?
Cannot remember) happens only during the transition from 0 bit to 1
bit of the clock signal.
For ddr, the transition happens in both transition rate, 0 bit
to 1 bit and 1 bit to 0 bit. This is because they make use of both
the clock signal and the inverse of the clock signal.
The clock signal input determines the speed of function of the
RAM. When you input a higher frequency clock signal, it will
function faster. Usually, RAMs will be able to take in a range of
frequencies, and this is the reason why you can have RAMs that are
backward compatible (those of same input voltage)