Most gamers and power users buy components to help them extract the most out of their computers. Deciding what RAM to pick is an essential part of the decision, as slower RAM can be a headache.
In this article, we’re looking at CAS latency and comparing CL16 to CL18 to help you make a better decision.
What is CAS Latency?
Before we get into the comparison, let’s look at CAS Latency first. CAS or Column Access Strobe Latency measures how fast your RAM can process commands received from the processors and prepare the required data.
Since it’s a measure of time, the general rule of thumb is that lower latency means better performance. However, other factors, including your choice of processor (Intel or AMD), play an essential role.
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CL16 vs CL18
CL 16 will perform better than CL18 as it’ll take two fewer cycles to prepare the requested data. If you compare a CL16 3200MHz RAM with a CL18 3600MHz RAM, the CL16 one will still outperform its CL18 counterpart despite a slower clock speed.
The average 3200MHz RAM module has a CL range of 14-16, while 3600MHz modules have a CL range of 15-19. While the latter has a higher memory speed, the former will perform better thanks to a lower CL latency.
The difference, however, is slight at around 5%. This means average people often overlook it and go with higher RAM speeds instead of lower CL. If your end goal is to maximise your PC’s performance, your goal should be to target the highest RAM speed with the lowest CL.
Processor’s impact on CAS Latency
AMD Ryzen CPUs are designed with an Infinity Fabric system called IF. IF has its own clock time features, which limit RAM clock speeds to around 2000MHz. If you have an AMD CPU, you should prioritise CL over memory speed.
On the other hand, if you have an Intel CPU, you’ll want to do the opposite. Since the clock cycle isn’t as tightly implemented as an AMD CPU, you’ll get more out of your processor with a faster memory speed. CL still plays an important role, though.
Another important thing to keep in mind is if you’re running dual or multi-channel memory. Make sure you’re running the same CL and clock speed across all your RAMs. Doing otherwise can cause latencies between RAM sticks causing slow performance.
|Latency||Lower CAS latency||Slightly higher CAS latency compared to CL16|
|Cost||More expensive||Relatively cheaper|
|Optimisation||Better optimised for reducing CPU lag.||Can give a relatively similar performance on Intel CPUs.|
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For most use cases, a CL16 RAM will outperform a CL18 RAM. The only place where CL18 has a fighting chance is with Intel CPUs, but even then, a lower CL RAM will ultimately help you get more performance.
However, if you’re building your PC for daily use and don’t exactly need every ounce of performance you can get, you can save yourself some money and go with CL18, as the difference isn’t exactly a lot.
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