I am using an STM32F446ZE Nucleo Board which does NOT have an external HSE clock. From CubeMX I set the clock input from the HSE and after in the clock configuration I set the system clock to 180MHz.
and in the clock configuration I set the PLL like this
The code generated by CubeMX seems to be correct also.My point is that even if I don't have an HSE in the board the uController works in 180MHz. How is this possible? What is the clock input after all?