|For best performance, the CPU & RAM should run at the same frequency...in other words, 1:1 ratio. Any other ratio setting will create a bottleneck in either the RAM or the CPU.|
Assuming a CPU Frequency of 200MHz & PC3200 RAM:
1:1 = 200mhz/200MHz
5:4 = 200MHz/160MHz - to get the RAM speed up to 200MHz, you'd have to raise the CPU freq to 250MHz. RAM is the bottleneck.
3:4 = 200MHz/266MHz - to get the RAM speed down to 200MHz, you'd have to lower the CPU freq to 150MHz. CPU is the bottleneck.