Motherboard just doesn't like the DIMMB1 and DIMMB2 slots (2 RAM slots away from CPU).

[20PeterBread01]

Specs:
MSI X370 Gaming motherboard
AMD Ryzen 5 1600X CPU
MSI GTX 1060 3GB GAMING X GPU
Corsair Vengeance RGB 2x8GB

Basically, only DIMMA1&2 RAM slots work properly.

If plug all the 2 RAM sticks to the DIMMB slots, the speaker will beep 3 long times, which I think is RAM error.

If I plug 1 RAM stick to the A slots and other to the B slot, it will ask me to either press F1 to enter BIOS or press F2 to continue. If I press F2, it will again, indicate RAM error and won't boot. If I press F1, I will enter BIOS, where it will tell me that there's only 8 GB of RAM. However, if I go to Board Explorer (where it displays all the devices plugged in to the motherboard), it WILL RECOGNIZE BOTH of the RAM sticks. Basically it recognises both, but doesn't include 1 of them (probably the one plugged into DIMMB slot).

So, the only thing I can do is to plug both of them to the DIMMA1&2 slots, which I can't because of the Air Cooler.

 

[cin19]

1) Update the BIOS, also the chipset driver https://support.amd.com/en-us/download/chipset?os=Windows%2010%20-%2064
2) Try low the RAM to less 3000mhz.
3) may consider to RMA the MB, if you are sure the RAM are good.