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What does the CL number mean on a RAM module?

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Recently I was looking to upgrade a laptop, to add more RAM, and I noticed that each module had a “CL” number. That got me curious to do a bit of research. Here is what I find out!

CL stands for “CAS Latency” on a RAM module. CAS stands for “Column Address Strobe”, and it is a measurement of the delay between the memory controller requesting data from the RAM and the RAM sending the requested data.

CAS Latency is the number of clock cycles that elapse between the memory controller sending a read command to the RAM and the RAM responding with the first piece of data. A lower CAS Latency value indicates that the RAM can respond more quickly to requests from the memory controller and can lead to faster overall system performance.

For example, if a RAM module has a CAS Latency of 16, it means that the RAM requires 16 clock cycles to return the first piece of data after the memory controller sends a read command.

In summary, the CL value on a RAM module stands for CAS Latency, which is the delay between the memory controller requesting data from the RAM and the RAM sending the requested data. A lower CAS Latency value can lead to faster system performance.