1. What is CAS Latency?

CAS Latency (Column Address Strobe Latency) is the delay time between when a memory controller requests data and when the data is available. It's a crucial performance metric for RAM modules, measured in clock cycles.

2. How Does the Calculator Work?

The calculator uses the CAS Latency formula:

Where:

• \( CL \) — CAS Latency in clock cycles
• \( \text{Data Rate} \) — Memory speed in megatransfers per second (MT/s)
• \( \text{True Latency} \) — Actual delay time in nanoseconds

Explanation: The formula converts clock cycles to actual time by accounting for the memory's clock speed. The data rate is divided by 2 because DDR (Double Data Rate) memory transfers data on both the rising and falling edges of the clock cycle.

3. Importance of CAS Latency Calculation

Details: Understanding true latency helps in comparing memory modules and optimizing system performance. Lower latency generally means better performance, though it must be balanced with other factors like memory speed.

4. Using the Calculator

Tips: Enter the CAS Latency (CL) value from your RAM specifications and the data rate (in MT/s). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is true latency important?
A: It allows direct comparison between different RAM modules by converting clock cycles to actual time (nanoseconds).

Q2: Is lower CAS latency always better?
A: Generally yes, but higher speed RAM with slightly higher latency may still perform better in many scenarios.

Q3: How does DDR affect the calculation?
A: DDR memory's effective clock rate is half its data rate, which is why we divide the data rate by 2 in the formula.

Q4: What's a typical CAS latency value?
A: For DDR4, common values are CL14-CL19. DDR5 typically has higher CL values but compensates with much higher data rates.

Q5: Can I use this for non-DDR memory?
A: No, this calculator is specifically designed for DDR memory. SDRAM would use a different calculation.