Is Speed or Latency More Important When Choosing RAM?

When choosing components such as a new kit of DRAM for an upgrade or an entirely new build, memory transfer speed will generally get the most attention. Transfer speed (or transfer rate) can be thought of as "how fast will this file on my hard drive be copied to my system memory." That said, does memory latency matter and is it more important than transfer speed?

Memory latency can be thought of as "how quick will my system memory respond to a request". This is usually measured in nanoseconds and expressed by a CL rating. To get the true latency of a kit of RAM in nanoseconds, you'll need to do some math.

(Real Latency) = CAS Latency x 2000 / Data-rate

For example, the real latency (in nanoseconds) of a kit of VENGEANCE DDR5 rated for 6000MT/s with CL36 would be calculated as follows:
36 x 2000 / 6000 which would give us 12 nanoseconds

Memory latency in most consumer kits is generally good enough for most applications: basic office work, web-browsing, most gaming applications, etc.

Memory latency becomes important when your memory is constantly being accessed, meaning that your memory kit needs to respond and act on a request as fast as possible.

Applications that benefit from lower latency would include: large database operations and games that push massive physics/environmental simulations, and ultra-high framerate targets where your system becomes more CPU-limited (waiting on the CPU to finish a task).

When picking a new kit of RAM, it's recommended to first identify kits of memory with the preferred configuration and total capacity you need for your system, then sort by transfer rate, and finally you can further dial things down by latency.

If you're building a new system or need help finding a compatible kit of memory, be sure to check out the Memory Finder or our full PC Builder that'll help guide you through component selection!