Anyone have an idea why my rx480 rigs always have lower current hash values to reported on ethermine pool while my 1070 rigs always report more current than reported? They both have been running for a week or more consistently.
What percentage difference are we talking about here?
You are probably experiencing variance. Meaning that the speed you see per GPU says 30MH/s is just an estimate of what hashrate you should get in the long run. However it depends on how many shares you actually found. This number can be higher or lower than your actual hashrate. Most likely always lower since you got dev free mining, stales and might get internet connection problems.
Eventually as time -> infinity you will find its more and more close to your true hashing rate.