As stated by others a while ago:
Since the driver option is officially discontinued, we lost the ability to adjust the minimum state/voltage of Vega FE through Wattman. With the latest 19.4.3 Adrenalin driver on Vega FE, my system still have random dxgkrnl.sys + atikmpag.sys BSOD during idle.
CPU: Ryzen 2700X
Motherboard: ASRock x470 Taichi
OS: Windows 10 x64 1809
Even with the Pro driver, crashes still occur but not as often. Setting the minimum state to State 1 or increasing the State 0 voltage will stabilize the FE at idle, not even a single crash for a month without rebooting.