Heck, many retailers even mention the memory kits CL in the product name.
What is CAS Latency(CL)?
The CAS latency of a memory kit can be described in various ways.
Credit:crucial.com
It can also be listed in memory timings like CL17-18-18-38.
In this case, the number after CL is the CAS Latency.
This latency is measured in nanoseconds for asynchronous DRAM and clock cycles for synchronous DRAM.
Credit:crucial.com
Besides CAS latency, there are three other types of primary memory latency.
These latency types are the numbers that we can see after CL in memory timings.
So you might check the CAS latency of those RAM kits from there before buying.
These information can come in handy if you want toincrease the RAM speed.
Memory Speed vs. CAS Latency: Whats the Difference?
Memory speed or RAM frequency is the data transfer rate of the memory kit.
If you want to know more, heres our in-depth guide onMHz vs MT/s.
How Does Different CL & Memory Speed Translate in Real-World Performance?
Now that you know what CAS latency means, you might wonder how CAS latency translates into real-world performance.
Although CAS latency is an important aspect, its not the definitive performance indicator.
you gotta consider both memory speed and CAS latency to determine the performance of a DRAM module.
Furthermore, not every app scenario would show better performance due to lower CAS latency.
Which One to Pick: High-Speed RAM or Low Latency RAM?
To be honest, theres no clear-cut answer to whether memory speed is more important or CAS latency.
It depends on a case-by-case basis.
But in most cases, a faster DRAM will provide better performance than a slower memory module.
On a side note, check out our guide onwhich memory slot to useto ensure the best PC performance.
Why Does DDR5 Have Higher CAS Latency than DDR4?
To be honest, its nothing new.
Previously, DDR3 kits also had lower CL numbers than DDR4.
So why do newer, better memory modules have higher CAS latency, and does it affect performance?
Well, as weve discussed earlier, memory speed and memory latency are more important than CAS latency.
Furthermore, the difference in CL numbers comes down to how they are calculated.
For example, CAS latency=Memory latency(ns)Clock Cycle Time(ns).
So, the CAS latency for a DDR5-4800 kit is 16.67ns0.42ns=40ns.
Meanwhile, a DDR4-2933 kits CAS latency is 14.32ns0.68ns=21ns.
So dont worry about the higher CAS latency of DDR5 compared to DDR4.
A CL40 DDR5-6000 memory kit will blow a CL17 DDR4-3600 DRAM kit out of the water in real-world performance.
Heres our detailedcomparison between DDR4 and DDR5 memory modules.
Frequently Asked Questions
Is higher CAS latency better?
Higher CAS latency means a longer delay in DRAM operation, which can slow down your PC.
What is a good CAS latency?
For DDR5 memory kits, C32 to C36 is an ideal range for CAS latency.
On the other hand, C15 to C17 is considered good CAS latency for DDR4 modules.
Can I mix DRAM modules with different latencies on my PC?
Yes, you could mix DRAM modules with different latencies, but Id advise not to do so.
Even in the best-case scenario, youd be running the memory modules at the slower memorys timings.
