Resolved. Not sure why they were performing better 2 weeks ago but I reduced the frequency. Minimal hardware errors now and just about averaging 600mh/s across all 4. Back to 100%

Last 4 days efficiency has been below 75%, mostly right around 65% and greatly diminishing profits. Noticed hardware errors through the roof on a couple of the ASICs, ten of thousands within hours. This morning made adjustments and lowered frequency from 475 to 450Hz and errors have greatly reduced....