When the computer crashes when activating Smart-5, what Error messages do you get? BSOD Error messages?
Might be a configuration issue in your Motherboard's BIOS or SIV may be incompatible with either Radeon Driver or Ryzen Master or it has a conflict. SIV doesn't control the GPU Fan correct? Just the Computer Case Fans and CPU Fan.
Can you upload DXDIAG.TXT. Sometimes that will indicate what specific programs are having problems on your computer. Also might want to check Windows Reliability Report that also indicates what software or what areas of Windows are having issues.
Your motherboard has a very new BIOS update. Try updating the BIOS and see if you still have problems:
- Update AGESA 18.104.22.168