A leaked slide shows that the upcoming Ryzen 5000 chips should be able to achieve higher infinity fabric clock speeds compared to their predecessors. Turkish website Technopat mentions this.

The slide claims that ddr4-4000 is to Ryzen 5000 what ddr4-3800 was to Ryzen 3000. That speed was relevant with the Zen 2 chips because it was generally the highest possible memory speed with the infinity fabric in 1: 1 mode. This also seems to be the case for Ryzen 5000: according to the slide, memory and fabric clock is the most cost-effective method for tinkering with the chips. Since ddr4-4000 has an actual clock speed of 2,000 MHz, that means that that speed can in all probability be (reasonably) achievable.

Memory management in AMD Ryzen processors is divided into three basic elements. The memory controller used by AMD and Infinity Fabric management, which manages the components within the CPU, is very important.

• Infinity Fabric Clock (fclk) : Manages how fast CPU cores can communicate with CPU components and SoC controllers. (Such as PCIe, SATA, USB)
• Memory Controller Clock (uclk) : Manages how fast the memory controller can receive / transfer commands from RAM.
• Memory Clock (mclk) : Frequency of main system memory.

As a result, RAMs will work more stable with new generation Ryzen processors. Thus, users will be able to reach higher frequencies and make fine adjustments.

DDR4-3600 remains the "sweet spot" and AMD's recommendation for the Zen 3-based processors, which are also specified with up to DDR4-3200. The new optimum, however, is DDR4-4000 with a synchronous IF or fabric clock (FCLK) and memory controller clock (ULCK) of 2,000 MHz.

Infinity fabric clock uplift would make DDR4-4000 possible for Zen 3