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Perfect Timing: DDR Performance Analysis

The Magic Word Is "CAS-Latency"

Users that are less experienced may have heard of the catchwords CL2 or CAS2 already. Unfortunately, only a few dealers are able to explain the meaning of these equivocal words. Attempts to explain sometimes end with other equally vague terminology, such as "Cache Latency" or other funny expressions.

Latency is a type of waiting time - which makes sense in relation to memory chips. The "C" or "CAS" stands for "Column Address Strobe." To explain this term, we should start with the memory chip itself :

It’s best to imagine a memory chip as some kind of storage matrix or table. In order to address each position, the matrix is organized in rows and columns. Thus, CAS is the column address strobe. As you can imagine, there is also a row address strobe (RAS).

From top to bottom : Infineon 512 MB DDR266 registered DIMM with ECC (72 instead of 64 Bit) for servers and workstations ; Corsair 256 MB PC2700 DDR-DIMM (up to 166 MHz) for overclocking ; Infineon 256 MB DDR-DIMM CL2 and Micron 128 MB DDR-DIMM CL2 - both are quite good modules.