Memory Latencies

RAM performance can be measured in several ways, but PC enthusiasts typically refer to the relationship between speed and latency. CAS latency is synonymous with the delay between the time at which a column address and column address strobe signal are presented to the memory module, as well as the time at which corresponding data is made available by the memory module. In layman’s terms, latency is essentially the time it takes to complete an operation with memory from start to finish. Memory speed determines the rate at which your central processing unit (CPU) can process data. With a higher clock rating, memory systems can read and write information very fast. The lower the latency, the faster your memory will be able to respond to command requests. In this guide, we dive headfirst into latencies to discover what causes delays and affects performance. Keep reading to learn more!

Beginner’s Guide to Memory Latencies
Memory latencies can be calculated by using the following formula:
• The total number of clock cycles the data must go through
• The duration of each clock cycle (measured in nanoseconds)

In other words, true latency is the product of clock cycle time multiplied by the number of clock cycles. Latency can be affected by several factors: the type of connection and the width of bandwidth. Furthermore, the number of routers between you and the server you’re connecting to can affect ping times dramatically. Communication back and forth between the memory controller and dynamic RAM, as well as capacitor refreshes, can also add latency.

Latency Myths and Misconceptions
There are many misinterpretations when it comes to latency. Product flyers and specification sheets refer to true latency as CAS latency (CL), but CL is only half of the equation. CL ratings traditionally specify the total number of clock cycles, but they have nothing to do with the duration of each clock cycle. CAS latency should not be used as the primary gauge of latency performance.

Using the correct formula for true latency, you can easily determine whether one module is, in fact, more responsive than another. Over time, memory speeds have increased as clock cycle times have decreased. Even though there are more clock cycles to complete, true latency stays approximately the same as technology matures.

Speed prevails as the most important metric for RAM performance because only CL increases as speeds increase. True latencies usually decrease or stay roughly the same, and CL ratings are often inaccurate or misleading.

Choosing the right RAM can make a tangible difference in your system’s performance. You can optimize your system by installing as much memory as possible. We hope that our in-depth exploration into memory latencies clears up any confusion you might have had about latency or RAM performance. Shop and build your PC with complete confidence. Choose a memory that suits your processor and your applications. Have questions about this article? Please contact XOTIC PC today to speak with an experienced support representative for additional information.