With...? You would need a chip... no?
It really depends on the chip. VC820 has no oc'ing feature, so oc'ing a chip will have to be done with a slotket, which only gives you 2 options (100mhz for celeryII's & 133 for PIII
100mhz chips) - which also means that you'll need a fcpga, rather than slot 1. I have no experience with Rambus, so other guys would have to help you out on that...