What motherboard?
What CPU?
XMP/DOCP enabled in BIOS or is set to auto?
Depending on the CPU .. the older the Ryzen, the more prone they were to run into "compatibility" issues with some RAM
IF your motherboard has 4 memory slots, be sure to install your RAM in slots A2/B2 (2nd and 4th slots away from the CPU socket)
Updating your motherboards BIOS can help resolve memory compatibility issues
IF you are running with XMP enabled and are running a 1st or 2nd Gen Ryzen, then you'll have to dial back your memory settings or just leave on auto until you upgrade to 3000 series or newer Ryzen to run your memory at 3200
Have you looked in your systems Event Viewer for logged errors when your system crashes?
How are your temps?
IF you are running a sub par power supply .. that can cause system instability when under load
Have you tried running just one stick of RAM at a time for testing purposes
Do you have the latest AM4 chipset drivers installed from AMD's website?
...stuff to look at/try/do if you want