vs3, quick question: why do the bitfurys in the nf6 design not run at their top frequency (6x3.5 = 21GH vs ~12.5GH)?
The throughput of SPI on MCP2210 is the factor of the hash rate
(the buffer size on MCP2210 is too short to feed a job to a bitfury in one transmission. Two transmissions are always needed. And more, the gap between two transmissions is another issue