Channel Bandwidth

WHAT IS channel bandwidth and how does it affect memory? Think of it as the maximum amount of data that can be transferred at any one time between your system and the memory installed. It’s calculated by using MT/s, the width of the memory bus, and the number of memory channels your system supports. So, for a typical Ryzen 7 1800X system, featuring 16GB (2x 8GB) of 3,200MT/s DDR4, it’s something like this. 3,200,000,000( 3,200MT/s)x 64 ( 64-bit bus)x 2( dual-channel )=409.6 billion bits per second, or 51,200 MB/s, or 51.2 GB/s.

That’s the absolute maximum amount of data the system could transfer between the memory and the processor at any given time, before bottlenecking. If you were to use a 4x 4GB kit on your dual-channel board, bandwidth wouldn’t increase, because the processor can still only read and write from two memory channels at a time (thus the dual-channel spec), despite the fact that you have four DIMMs installed. On the flip side, installing just one DIMM cuts that figure in half.

It’s worth noting that for most applications, dual-channel memory kits provide you with more than enough bandwidth for everything you want to do on your desktop. However, for applications that manipulate massive data sets, textures, and more, an increase in channel support can eliminate potential bottlenecks, because more powerful processors become more capable at manipulating larger data sets. 4K, 5K, and 8K video editing in After Effects, for instance, benefits greatly from having access to both a larger memory capacity and increased memory bandwidth, thanks to quad-channel support.