What happens if you put RAM with a frequency higher than indicated on the processor?

Question

Iron

Hello!
What will happen if you make such an assembly:
mother: Z370-P
processor: i3-8100
RAM: DDR4 2x4gb 2800MHz
Do not pay attention to the mother, I gave her as an example. I'm interested in starting a PC with such a bunch of percent-RAM and will it work fine?
PS Thank you!

Answer 1

The motherboard will lower the frequency of the bars

Answer 2

Options:
either agree on the mode supported by all participants via SPD or XMP and the system will work on these settings
or do not agree and the system will not start

Answer 3

Nothing :) the memory frequency will be lowered to the one at which it can work. If the memory is so new that the mother does not know it, the computer simply will not start.