Question about p4p800 dlx/memory

[madcap magician]

I bought this mobo a week ago and thought the 3ghz P4 i bought was a dud because it would only o/c to 3150. I'm using pc2700 at the moment and have been running it at 400 dual channel with no problems. Anyway I set the memory back down to 320mhz and was able to o/c the cpu to 3.8ghz. My question, or rather statement, is I thought the memory stays at 400 or 320 mhz even if the fsb is changed on this board. Anybody know for sure? I've looked around but haven't found an answer yet.