latency
When we see what a RAM’s CAS latency is, it is 4 numbers, such as 2-2-2-5, which correspond with CAS – tRCD – tRP – tRAS. You should be able to change the CAS Latency in your BIOS. In most BIOSes, it can be found under the “advanced chipset” menu, though it can be found in different areas in different BIOSes.
CAS stands for Column Address Strobe. This is the number of memory cycles that pass between the time a column is requested from the active page and the time the data is ready to send across the bus. This number is usually 2, 2.5, and 3, on DDR memory. This is actually the last part to come into effect.
RAS to CAS Delay is referred to as tRCD. This is the delay in memory cycles between the time a row is activated and when data within the row can be requested. This only happens when data is not on the active row.