how did you overclock the thing? Did you just do the normal and increase the FSB number? In that case the ram is still running far under its rated speed, and is not holding you back. Even if you set the divider to 3:2 the ram should still be OK. One other thing you should check is the PCI/AGP divider. I am not familiar with that board, but I think that it has a PCI/AGP lock. If that is the case set the frequency under the PCI/AGP setting to 33/66 or lock (or maybe auto). Also, what kind of temperatures are you getting in the bios, if your cooling is not very good that may be the problem.
As for overclocking your RAM, yes you can do that and get an increase in speed. What you will want to do is set the RAM/CPU frequency ratio to 3:2, and then your RAM will be running 3 fsb for every 2 that the CPU is.
good luck!