I have a RX 570 powered by an 800W PSU. I've tried everything to uninstalling the driver with DDU to going all the way back to the 18.X.X driver and It's still the same thing on any driver released. I can play for like 5-10 minutes and then my game freezes and crashes and says "Wattman settings have been restored because of system failure". I'm about to the point of taking the card out and selling it because this is honestly getting ridiculous. I've been wanting to play for 3 weeks now and no luck with anything I've tried. Fix the drivers AMD.
Every time it crashes you will need to set the power limit back to 50. It resets to defaults.
Your settings for power limit and fan and gpu are very similar to my RX 580. I will share my settings for Power Limit which you already have but more importantly my Fan and Temp curve. Do not use my core, voltage, memory settings. your card is different there. Just Power Limit and Fan & Temp. I think you are thermal throttling possibly and this would help that.