CL stands for CAS (Column Access Strobe) Latency, which is a term referring to the time that it takes to retrieve data from the module.
- CL2 and CL3 refer to the amount of clock cycles that it takes before the initial stream of data is sent.
- CL2 modules wait two clock cycles before sending data.
- CL3 modules wait three clock cycles before sending data.
- CL2 modules are faster since they only wait two clock cycles. Some systems may specify either CL2 or CL3 memory.