Memory frequency

[kapoli]

I have an Athlon 64. In CPU-Z, under the memory tab, it says my frequency is 200.3. What is the optimal frequency for memory? I have 2GB of RAM and when set to autodetect in BIOS, CPU-Z reports a frequency of 156. But when I take out two sticks and have only 1GB of RAM, CPU-Z reports frequency of 200. Why is this?

 

[pol II]

Perhaps your mobo downclocks the memory to 333MHz with 2GB.