CAS Latency

CAS latency is short for Column Address Strobe latency.

CAS latency is the time (in clock cycles) required to access a column of memory on a DRAM memory module.

A CAS3 rated memory module requires 3 clock cycles to address a column of memory, where a CAS2 rated memory module can accomplish the same task in only two clock cycles.

Three steps are required to address DRAM on a memory module, such as a DIMM:

1. Memory bank selection
2. Memory row selection (Row Address Strobe)
3. Memory column selection (Column Address Strobe)

CAS latency is sometimes abbreviated as CL.