it all depends on the motherboard chipset.....
Anyway...to the OP....if you're stable at 3ghz then you can put your HT link to 4...you always want to keep the HT link as close to 1000 as possible.
well, my nf4 ultra and this 590 run exactly the same. at a 9.5 multi...with memory settings of ddr2 400 (cpu/10 divider), ddr2 533 (cpu/8 divider), ddr2 667 (cpu/6 divider) and ddr2 800 (cpu/5 divider). the cpu/divider is from memory, so i mught be off on a couple. so actually, your divider number really depends on the cpu and it's stock multi, or what multi you choose to set it at, and the speed you set your ram to in bios.
i dont know of any intel chipset that works that way. but, i dont know everything
. from what i understand, setting intel's memory divider dictates the speed, but there is no actual ram speed setting that affects the divider/ram speed.
also, at a lower ht...i have not noticed a significant difference between running a 5 x multi and a 3 x multi. except with a 3x i know it will be stable. the difference is negligible in performance.
also, as far as fsb goes...
your cpu will probably push past 300, but it may not like it too much. just a heads up, you will have to work some on it to get much more than that.