as long as your ram speed is faster then your CPU for overclocking
basically DDR2800 is good for most CPU like q6600.
sometimes you may see some performance gain running your ram faster then your cpu FSB but i dont think it will be something that makes you go WOW!
and even before you didnt need stellar ram, just ram usually faster then your CPU so when you overclock, your RAM isnt the possible bottleneck stopping you from overclocking, or needing to run some ratio.