TechPowerUp reports AMD's upcoming Zen 2-based Ryzen 3000 series processors will support 3200MHz DDR4 memory. That compares to 2666MHz for the original Ryzens and 2933MHz for the Zen+ update.
The importance of system memory for AMD lies in the fact that the CPU's CCXs use the memory bus as a way to calculate their Infinity Fabric speeds, which allows for inter-CCX communication - higher memory data rates thus equal higher CPU performance as a whole. The increase in the base JEDEC specification support means that AMD have worked on adding a little grunt to their memory controller which should help improve IPC due to increased Infinity Fabric capabilities.
The site also heard AMD will "officially" support overclocking to at least up to 4400MHz DDR4.