You can change it but you can have it set to be in sync.
You need to use ratios to get that but you should be able to run your ram at ~ 166 with the FSB at ~225 (if your motherboard will go that high). I get a little confused with the dividers so I won't explain em' to ya just in case I switch stuff around (lol for some reason that confuses me lol, I swear I'm not dumb though), but your manual explains it so you just gotta figure out what ratio gives you the closest to desired resutls.