Why is CM4 core clock limited to 64 MHz while CM7 runs at full configured frequency? How to increase CM4 clock frequency?

[Prathiksha]

I am working on the NUCLEO-H755ZI-Q, which contains a dual-core STM32H755 (Cortex-M7 + Cortex-M4).

I configure the system clocks in CubeMX as follows:

• SPI1/2/3 Clock MUX: 400 MHz
• System Clock: Configured for high-speed operation
• CM7 core frequency: Correctly matches the configured value (e.g., 200 MHz / 400 MHz depending on settings)

However, when I debug or read the CM4 core clock, I always see:

• CM4 clock = 64 MHz
• It does NOT increase even when I configure higher values in CubeMX. 

Regards,

Prathiksha

[AScha.3]

How you "see" the 64Mhz ?