I also have a SP31 that won't give more than 4.7Th/s. I am beginning to think this is the maximum, a far cry from the advertised 5.5Th/s.
My unit is running @ 240v and close to 3Kw.
While it was advertised for 5.5Th/s I think you missed Guy's update:
The hash rate of the SP31 will be 4.9TH/s +- 5%. Power consumption will remain the same 3kW at the wall as in the previous SP30.
That update means fuck all after the fact, Guy once again overstated and under delivered. Was it another slow corner batch this time? Such an arrogant bunch ...