What is CAS Latency?

CAS stands for Column Access Strobe (conversely, RAS stands for Row Access Strobe) and CAS Latency is the amount of delay that you have to wait between the CAS signal and the data being pushed from the RAM pins. CAS2 latency essentially means we have a 2 cycle delay, and CAS3 has a 3 cycle delay: hence the lower the CAS, the lower the latency, and the better your performance.

The sequence of events is something like this:

• The "row" of the memory address is accessed and RAS is activated
• RAS-to-CAS delay
• The "column" of the memory address is access and CAS is activated
• CAS delay
• the data is pushed to the RAM pins