Will the RAM work correctly in a combination of 1866 + 1600 MHz?

Question

Iron

Good time!
Who is in the subject, tell me about this situation: there is an Asrock A75 Pro4-M motherboard with support for dual-channel DDR3 memory, two of the 4 slots are currently occupied and two Kingston KHX1866C9D3K2 / 8GX brackets are installed .
Question: if we install two more Kingston KHX1600C9D3K2/2G brackets and set the operating frequency of all modules to 1600 MHz, will the RAM work correctly as a whole in this configuration?

Answer 1

It will, but at the lowest frequency. In your case 1600 MHz

Answer 2

If the new RAM is supported by the motherboard, then yes.