well, to explain it, CL (which stands for CAS Latency) means the number of clock cycles before a certain piece of data is available for the memory controller to retrieve in order to process it. theoretically, a CAS latency of 9 would be better, but how the speed of the ram is actually determined is the cas latency multiplied by the time each individual cycle takes. for example, if we have a cas latency of 9 and each cycle took 3 milliseconds, it would take about 27 milliseconds whereas for a cas latency of 10 with the same cycle timing of 3 milliseconds would take 30 milliseconds, so theoretically, in that sscenario Cas latency of 9 is better, but what I'm saying here is that CAS is not the entire determination of RAM speeds.