An Overview of CAS (Column Access Strobe) Latency RAM

What Is CAS Latency

CAS (Column Access Strobe) latency refers to the delay time between the READ command and the time data gets available. The CAS latency is also called CL. You will see a list of timing on the RAM like CL16-18-38 and CL14-14-34. The number behind the CL stands for the RAM kit’s CAS latency.

How the CAS latency RAM is measured? The interval is specified in nanoseconds (absolute time) in asynchronous DRAM. Differently, the interval is specified in clock cycles in synchronous DRAM.

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As the latency is associated with plenty of clock ticks rather than absolute time, the exact time for an SDRAM module to respond to a CAS event may vary because of different uses of the same module. What does RAM CAS latency mean? Keep reading the following content to learn the details.

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What Does CAS Latency Mean

The RAM module’s CAS (Column Address Strobe) latency is how many clock cycles the RAM takes for accessing the specific set of data in one of its columns and making the data available on its output pins.

Generally speaking, a RAM kit with a CAS of 16 takes 16 RAM clock cycles to finish this task. In other words, the lower the CAS latency is, the less RAM is required. In addition, you should also note that the CAS latency can be described via several ways. To be specific, a RAM kit with a CAS latency of 16 can be written as CAS 16 or CL16.

Moreover, two different RAM kit may have the same data transfer rate. For instance, both the Team Group Delta Tuf Gaming RGB DDR4-3200 and G.Skill Trident Z Royal DDR4-3200 have a transfer rate of DDR4-3200.

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RAM Latency vs RAM Speed

The data transfer rate of RAM tells you how many mega transfers (1, 000, 000 data transfers) the RAM within one second. For example, a DDR4-3200 RAM can deliver 3200 mega transfers per second.

What about RAM CAS latency? It can help you learn the performance of RAM as well. As mentioned earlier, the CAS latency RAM tells the number of clock cycles it takes for the RAM to send data. At the same time, you should also consider the duration of each cycle to obtain an overview of RAM’s total latency.

RAM latency vs RAM speed: which one is more vital? Analyzing from the above description, you can find that both the RAM latency and RAM speed are important for RAM.

Though the DDR4 RAM is newer and has better storage density and power efficiency compared with DDR3 RAM, it has higher CAS latency. According to investigation, DDR3 usually has a CAS latency of 9 or 10, while the DDR4 has at least 15 CAS latency. Thanks to faster clock speeds, the DDR4 has a better overall performance than DDR3.

You may also be interested in this: What Are the Differences Between DDR3 and DDR4 RAM

Bottom Line

After reading the post, you may learn what CAS latency RAM is and some addition information about it. Hence, you will get a comprehensive understanding of CAS latency RAM as long as you finish reading. Hope this post can be helpful for you. Here comes the end of the article.