Quote from: dualminer on July 05, 2015, 09:42:50 PM

Quote from: philipma1957 on July 05, 2015, 08:54:07 PM

I can buy 100 LTC for a lot less then 40 of these chips

SF3301 chip does have the best power efficiency in both BTC and LTC mining.

LTC power measurement
Voltage(V)   Frequency(MHz)   Power(W)   HashRate(MHahs)   W/MHash/s
0.8   450   2.18   1.21   1.79
0.9   700   4.34   1.89   2.30

BTC power measurement
Voltage(V)   Frequency(MHz)   FBB(V)   Power(W)   HashRate(GHash)   W/GHash/s
0.6   225   0.0   10.98   36.00   0.31
0.8   625   0.0   53.60   100.00   0.54
0.6   300   +- 0.6   14.88   48.00   0.31
0.8   870   +- 0.6   77.68   139.20   0.56
0.6   450   +- 1.1   23.28   72.00   0.32
0.8   950   +- 1.1   97.28   152.00   0.64

Having the best power efficiency means little if the device is priced unreasonably. From this table the most reasonable setting for BTC mining seems to be 72GH/w at an efficiency of 0.32W/GH/s (efficiencies above 0.5W/GH/s have no advantage over current competitors' hardware). Let's compare that with an S5. You'd need 16 sfards chips @72GH/s to achieve 1155 GH/s. Each chip is currently offered for $30, so that's $480 just for the chips. Then you'd need to add the supporting hardware around it; printed circuit boards, a controller, DC-DC converters, supporting circuitry, a case, connectors ... and a markup. How much would such a miner sell for if the chips themselves are $480? The S5 goes for $360 US ...

And in terms of efficiency, what's important is the *system* level efficiency; chip-level efficiency is not that useful beyond academic discussion. Even Spondoolies' current Rockerbox chip can easily be shown to achieve better than 0.4W per GH/s. Put those chips in a practical miner, with supporting circuitry and DC-DC converters, and you quickly see that chip-level efficiencies can no longer be achieved on a system level.

As far as I know, there are no 'practical miners' made with the SF3301 yet. And by 'practical' I'm referring to something that can compete on a GH/$ level with current miners such as the $360USD 1155GH/s S5. Until system-level specs are demonstrated for an sfards-based miner, there's little point in discussing chip-level efficiency.