You have to manually set your CPU voltage, and at least another voltage, since many things are dependent on the FSB clock that you are playing with.
I suggest keeping your ram speeds equal or less than the 800mhz they are meant to work on, as overclocking ram will not benefit you so much
As for voltages, DO YOUR OWN RESEARCH, but I think up to 1.4V is safe for that CPU, usually people would use 1.3V for daily, and 1.35V as a safe max daily.
However, since your CPU is kinda old, maybe drive it with a lot of voltage so you can have a high clock and get the rest of life from it.
I think the other voltage you have to play with is the NB voltage.