DDR5-6400 Confirmed as Sweetspot Speed of Ryzen 9000 "Zen 5" Desktop Processors
https://www.techpowerup.com/324023/ddr5-6400-confirmed-as-sweetspot-speed-of-ryzen-9000-zen-5-desktop-processors
""As part of the update, Ryzen 9000 "Granite Ridge" should be able to run DDR5-6400 with a 1:1 ratio between the MCLK and FCLK domains. This is a slight increase from the DDR5-6000 sweetspot speed of Ryzen 7000 "Raphael" processors. AMD is reportedly making it possible for motherboard manufacturers and prebuilt OEMs to enable a 1:2 ratio, making it possible to run high memory speeds such as DDR5-8000, although performance returns with memory speeds would begin to diminish beyond the DDR5-6400 @ 1:1 setting. Memory manufacturers should launch a new wave of DDR5 memory kits with AMD EXPO profiles for DDR5-6400.""