I recently build 3 identical computer's for my wife's office.
Windows 10 Pro
Ryzen 3 3200g
8gb Patriot Viper 4 DDR4 3000
ASRock B450M-HDV R4.0
Crucial 500gb SSD
Corsair CX450M 450 watt PSU
At first I was having issues with 2 computers blue screening (hadn't gotten around to fully testing the 3rd one for blue screens). After running memory diag tests (no errors), chkdsk, and sfc /scannow, I was still having issues. I updated all drivers as well as ensured BIOS was latest version. I began checking for faulty RAM by pulling out a stick and testing. I found in the BIOS that the RAM speed was set to auto detect but showed DDR4 2133 I set it manually to DDR4 3000 and couldn't get the computer to boot. I pulled a stick, got it to boot, and set it to DDR4 2933 and was able to get back into windows.
Since then the blue screens have ceased as far as I can tell. I had my wife try to break it by browsing watching videos etc. After about 30 mins she told me it rebooted with no BSOD. I got back in and started messing around and was able to get it to reboot again while playing a video. Upon reboot I double checked that i had the latest Graphics drivers available from AMD and also installed the latest B450 chipset drivers from AMD. I tried again and the computer still rebooted during video playback. I also tried disabling virtualization in the BIOS with no results.
All of this has lead me to believe that there is either an issue with the graphics driver, CPU, RAM, or some compatibility issue but i am not sure where to start. I checked the event viewer and there is nothing that stands out in the system logs as to why it rebooted. Just a critical error that it rebooted unexpectedly.