One question for all the expert oc guru. If i ran cpu:ram asynch would it effect the performance compared to running sync.

On intel, there is bottlenecking effect i notice, on AMD64 is it the same?. I heard about the pros and cons of the mem controller,
I was looking for answers at XS and Hardforum, but couldnt find any. So here is the question, AMD64 has bottlenecking effects?
I would be really glad if somebody could enlightened me with these. I plan to get AMD64 3800+ but since i have a bad RAM might as well i used dividers-so im glad if anybody can help me.
If the effect is quite serious, i would think of getting 3200+ coupled with a good pair of RAM.