Well the divider's are already set, it is a matter of changing their profiles.
What does the SPD page show for your ram? I can't tell you much unless I know a little more.
Say for instance, you have ddr2 1066 ram. With a bus clock of 200, you would need a divider of 3:8 to achieve the 533mhz needed to have Double Data Rate 2 1066 ram. 200/3*8=533*2=1066
Now lets say theoretically your ram is not stable past 1077 (a 5.5mhz jump).
If you push past 202 on the bus clock, your ram now is unstable and will cause your system to crash even if your cpu and bus clock can handle those speeds.
What you would need to do then is lower the ratio. Say you have a 1:2 divider.
If you bump down to the 1:2 divider, you now have 202/1*2=404*2=808. So you have ram running at 404mhz now, or ddr2 808.
Now you can keep pushing the cpu/bus further in theory.
This was all just an example, I haven't had any personal experience with 64 x2's, your mobo, or your ram.