Techware Labs took a stick of Crucial’s PC2700 DDR RAM, and used it to test different ram settings and their effect on speed. Everybody knows that there is a performance difference between DDR200 (pc1600) and DDR400 (pc3200). But there are also other factors, like CAS that affect performance.
“From our results, the most important factor in memory bandwidth is the speed of the memory clock. This would suggest a certain desirability to sacrifice the other memory timings in hopes of pushing the memory speed higher. However, as our results revealed, the speed of the memory combined with CAS latency has the most affect on the overclockability of a memory stick (our test memory would not run at the more aggressive speeds and CAS latencies).”
A more detailed analysis can be found here.