Don't edit anything in wattman. It's really bugging. Use ddu and install driver you can use afterburner to set a fan curve.
Everytime I set anything in wattman I get bsod black screen game crash.
I have this same issue. RX5700XT with R5 3600 and Asus X370 Prime Pro running Windows 10. I have try 19.7 from 1 to 5.
All of them give me the BSOD atikmdag all while just browsing facebook.
Full system specs
AMD R5 3600
Asus Prime X370 Prime Pro
Corsair DDR4 2400mhz 8GB x2
Powercolor Reference RX5700XT
500GB Samsung EVO SSD + 1 2TB HDD + 3TB HDD
Antec High Current Gamer 520W PSU
I ended up switching to a different card since I dont have time to troubleshoot.
I have posted this elsewhere, but I was also having problems my fix:
Update chipset drivers to latest version (mine was B450 chipset)