Quote - Did I understand correctly that your minimum shading rate is 0? That's really low. Try increasing it to say 0.2 or 0.15.  Also lower pixel samples to 5 and then increase it later.

I always keep my shading rate at .05 but that WILL substantially increase render time. If you think that may be your problem, increase that to the default as was mentioned earlier (which is .20 IIRC). Just be warned that it will also lessen the detail somewhat.

Laurie