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IT Support & Hardware · Advanced

CAS Latency (CL)

The number of clock cycles between a memory read command and the data becoming available.

Definition

CAS latency is listed as CL (e.g., CL16), and real latency in nanoseconds depends on both CL and speed: about CL x 2000 / MT/s. A higher-speed kit with higher CL can have similar true latency to a slower kit with lower CL. Lower true latency improves responsiveness.

Example

DDR4-3200 CL16 has about 10 ns latency; DDR5-6000 CL30 also has about 10 ns.

Exam tip

Do not judge memory by CL alone; combine it with speed.

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