What is CAS Latency in RAM?

CL stands for CAS Latency. It is a programmable register in a SDRAM which sets a series of time cycles in between a distribution of a READ authority as well as when a interpretation comes out. Smaller series for CL indicates faster SDRAM inside of a same frequency.
There is some case that your computer and on the RAM said that it had latency of 8-8-8-24. When I looked in the bios and on cpuz it said that it was walking at 9-9-9-24. Regrettably, this is because you make the error of buying RAM at 1600mhz when my motherboard will only support upto 1333mhz. It still works but runs at 1333mhz.
When you open the memory tab from cpu-z, there will be some number. You can read it from top to down :

667 --> your memory is walking on 1333MHz

7
7
7
20 --> The latency is 7-7-7-20