Oc the gpu's to much? Check for memory errors with something like hwinfo64 or try lowering your dcr intensity? "You can change the intensity in runtime with "+" and "-" keys and check current statistics with "s" key."
I tried going stock by turning off Afterbuner, no help. I swung the intensity in both directions and I checked for memory errors of which there were none.
Still 100% reject rate. I tried it in dual mining for straight ETH, still no dice. Like I said I'm at a complete loss.