>>106405873
The UCLK:MEMCLK ratio is probably automatically set to the suboptimal 1:2 mode; it's the default behavior (according to AMD) if the memory speed exceeds 6000MT/s.
Go to the BIOS & lower the memory speed to 6000MT/s, primaries to 30-40-40, and MEMCLK:UCLK ratio to 1:1.

>>106260571
Get a 6000MT/s CL30 memory kit if you're not comfortable setting manual speed & timing in the BIOS.
6400MT/s isn't guaranteed to run at the optimum 1:1 UCLK:MEMCLK ratio; stock board behavior recommended by AMD is to set that ratio to 1:2 at speeds above 6000.

>>105683862
SK Hynix makes DDR5 memory chips (ICs) that overclock higher while stably keeping timings lower compared to other chip manufacturers like Samsung and Micron.

CL32 6400MT/s is better, but you may have to downclock it to 6000MT/s and adjust the primary timings to 30-40-40-96 if your CPU's memory controller can't run it at 1:1 memory speed: memory controller mode (MEMCLK : UCLK = 3200MHz: 3200Mhz).

If you have a hard time understanding this, ask some Russian PC hardware forums.
There are plenty of Russian-speaking PC hardware enthusiasts.

>>105616368
Get a 6000MT/s CL30 memory kit if you want a hassle-free experience.
The memory controller in these Ryzen CPUs isn't guaranteed to run that 6400MT/s spec at the optimal 1:1 ratio (memory speed : controller speed).

You can get the 6400MT/s EXPO kit and dig through the BIOS to make sure the 1:1 MEMCLK:UCLK ratio is enabled, but I'd run some stress tests to make sure the configuration is stable.