Need basic info about memory latency

[Denis54]

I am a newbie and would like to know what are the most frequent dual channel memory latency numbers. I understand 2-2-2-5 is the fastest and 3-4-4-8 is the slowest.

Are there any web sites that explain what these numbers are all about?

 

[Corporate Thug]

found this in another forum

*The first would be the CAS (Column Address Strobe) Latency - Controls the latency between the read command and the time the data becomes available.
*Second is RAS (Row Address Strobe) to CAS delay - Controls the latency between the active command and the read/write command.
*Third is RAS Precharge Delay - Controls the idle clocks after issuing a precharge command.
*Fourth is the Active Precharge Delay - Controlled by the SPD (Serial Presence Detected). It controls the number of DDR clocks used for a DDR Parameter