This has been an intermittent problem, it'll go away for a few weeks at a time and then resurface. I have the Fatboy RX590 8GB edition and it usually only occurs while I'm playing Final Fantasy XIV. Both my monitors will go black, flicker a few times and then go into sleep mode as if there is nothing to be displayed. The sound still plays and I can tell from the sounds that inputs from my keyboard still register so I know the game, and the rest of my PC has NOT crashed.
Here is my entire PC specs
Coolermaster Masterbox Pro 5 RGB case
Asus B450F motherboard
Ryzen 7 2700x with Wraith Prism cooler
16GB Gskill TridentZ DDR5 RGB RAM
Radeon RX590 8gb Fatboy graphics