I mean i get avalon 1047 for under $100 so why should someone use an s7 these days?
120 volt power for the s7.
and you can use an atx psu for the s7 which is quiet.
he should change to an s9 which is better and can use a quiet atx at 120 volts.
he can mine bch at viabtc.com
he can mine xec at viabtc.com
xec has a crazy upside if it ever rallies