Lowering clock speed

[eXcelon7574]

I know this is probably a basic question, but I have searched the forums and I really haven't found the answer I have been looking for. Anyways, I currently have 2GB of DDR2-533 memory, however I have not messed with overclocking my processor because my temps are pretty high, would it be best for me to lower the memory clock in bios to 400mhz and then lower the timings? Would this give me the best performance? Thanks.