I am using 3.72 and these settings yield 840
“api-allow” : “W:127.0.0.1”,
“api-listen” : true,
“api-mcast-port” : “4028”,
“api-port” : “4028”,
“expiry” : “120”,
“hotplug” : “5”,
“log” : “5”,
“queue” : “1”,
“scan-time” : “30”,
“scrypt” : true,
“shares” : “0”,
“gpu-threads” : “1”,
“gpu-dyninterval” : “7”,
“gpu-engine” : “875”,
“gpu-fan” : “50”,
“gpu-platform” : “0”,
“gpu-memclock” : “1500”,
“gpu-memdiff” : “0”,
“gpu-powertune” : “30”,
“gpu-vddc” : “0.000”,
“intensity” : “20”,
“temp-target” : “95”,
“temp-overheat” : “95”,
“temp-cutoff” : “99”,
“temp-hysteresis” : “3”,
“vectors” : “1”,
“worksize” : “512”,
“lookup-gap” : “2”,
“thread-concurrency” : “27400”
}