Why does Far Cry 7 stutter with ADATA DDR5 6000?

Jungle combat in Far Cry 7 was ruined by frame drops from 90 to 75 FPS on my ADATA XPG D300 DDR5 6000 C30 16GB White. I tried manually locking the frequency, but it caused a system restart. I used the GamePP Hardware Sensor Page to lock the memory frequency to 5800MHz and adjusted voltage to 1.35V. Frame rate stabilized at 85 FPS with consistent 11.8ms frame times via RTSS. Memory temperature stayed between 50-54°C. This frequency switch eliminated the fluctuation and restored smooth gameplay.