My neighbor has ch-6, it likes voltages, but it hates timings under 2.5-4-4- or 3-3-3. Can get to about 230fsb pretty well on those timings.
Ch-5 can stay tighter, most of the time it will run 2-3-2, more voltage it should be able to run 2-2-2. Won't scale as well with 2-2-2 as bh-5, but can hit around 240-260 with 2-3-3 or 3-3-2.
Sorry if I'm butting in