Here is my 7.3mh 280x config you need to fix the memclock and gpu engine not sure about more for the 290
{
"pools" : [
   {
      "url" : "stratum+tcp://adn.minebig.com:3399",
      "user" : "user",
      "pass" : "x"
   }
]
,
"intensity" : "13",
"nfactor" : "6",
"xintensity" : "0",
"rawintensity" : "0",
"worksize" : "256",
"lookup-gap" : "2",
"thread-concurrency" : "24000",
"shaders" : "0",
"gpu-threads" : "2",
"gpu-engine" : "1080-1110",
"gpu-fan" : "30-80",
"gpu-memclock" : "1450",
"gpu-memdiff" : "0",
"gpu-powertune" : "20",
"gpu-vddc" : "0.000",
"temp-cutoff" : "95",
"temp-overheat" : "85",
"temp-target" : "70",
"api-mcast-port" : "4028",
"api-port" : "4028",
"auto-fan" : true,
"expiry" : "10",
"failover-switch-delay" : "60",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"log" : "5",
"no-pool-disable" : true,
"no-client-reconnect" : true,
"queue" : "1",
"scan-time" : "7",
"tcp-keepalive" : "30",
"temp-hysteresis" : "3",
"shares" : "0",
"kernel-path" : "/usr/local/bin"
}

And .bat
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
del *.bin
Color 0A
sgminer