The decoder memory bandwidth depends on frame rate, resolution, color depth, chroma format, and Decoder profile. The AMD LogiCORE™ IP provides an estimate of decoder bandwidth based on the video parameters selected in the GUI.
AMD recommends using the fastest DDR4 memory interface possible. Specifically, the 8x8-bit memory interface is more efficient than 4x16-bit memory interface because the x8 mode has four bank groups, whereas the x16 mode has only two and DDR4 memory allows for simultaneous bank group access.