OCIA.net has posted part 2 of their overclocking guide.

Speaking of memory dividers, this is another setting that sometimes confuses people. While the idea of memory ratios or dividers have existed for a while, AMD users were always told not to use them. I think it was drilled into our heads. Now that we can use them we need to understand that the exact ratio changes slightly depending on the CPU multiplier you use. The reason for this is with the memory controller built into the processor, any divider used takes into account the CPU Multiplier when calculating the ratio.

Overclocking Guide, Part II