CAS latency (Column Address Strobe latency) measures how quickly your RAM can deliver data once your processor asks for it. It's measured in clock cycles, so a CAS latency of 16 means the memory needs 16 clock ticks to find and return the requested information. Lower numbers are faster.
Think of it like this: you ask a librarian for a specific book. CAS latency is how many seconds it takes them to fetch it from the shelves and hand it to you. If your RAM has CAS 16 and your friend's has CAS 18, your RAM responds two cycles quicker.
CAS latency works alongside memory speed (measured in MHz). A faster clock speed can offset higher latency. For example, DDR4 memory running at 3600 MHz with CAS 18 might perform similarly to 3200 MHz DDR4 with CAS 16, because the faster clock compensates for the longer wait.
What to look for when buying:
- Match your motherboard's supported speed and latency specifications.
- For gaming and everyday use, CAS 16 to 18 is typical and acceptable.
- Professional workloads (video editing, 3D rendering) benefit from lower latency, but speed matters more.
- Lower latency RAM usually costs more; the performance gain in real-world use is modest for most people.
When choosing RAM, don't fixate on CAS latency alone. Check the complete profile: speed, latency, and your system's actual demands. A faster, slightly higher-latency kit often outperforms a slower, lower-latency one.