Adjusting the multiplier only affects the CPU and is less complicated. using the FSB also changes your memory speed. it has nothing to do with memory size. Since your changing the memory speed you also have to worry about it and the memory controller being stable, not just the CPU which makes the knowing the source of a failure hard.
There are plenty of overclocking guides. basically use the multiplier to get as high as you can and stable. Then if you want to overclock the memory reduce the multiplier and up the FSB as much as you can while staying below the CPU limit. When it fails back off.
This what I was searching for.
Thnx a ton !