There is one last BIOS update that ASUS offered that I have not installed (don't fix what isn't broke) but the update for 2nd & 3rd gen Ryzen's is installed. It may not be a bad idea to go ahead & install that last update.
If I recall correctly, the 1st gen Ryzen CPU / MB combo were fussy about accepting RAM. What I was assured by online store to be fine had to be exchanged for RAM approved on the ASUS list.
The Ryzen 1700 is 8 core, 3900X is 12 so probably some changes in the BIOS Processor box.
Will I need any of my passwords after resetting CMOS? And, will Microsoft need to be called because a detected change of hardware? I don't want to be surprised by not having that & other info.