Here's what I'm using for r9 290:

{
"pools" : [
   {
      "name" : "darkcoin",
      "url" : "",
      "user" : "",
      "pass" : "",
      "pool-priority" : "0"
   }
],
"api-allow" : "W:127.0.0.1",
"api-listen" : true,
"expiry" : "2",
"queue" : "0",
"scan-time" : "1",
"scrypt" : true,
"auto-fan" : true,
"auto-gpu" : true,
"gpu-threads" : "2",
"gpu-engine" : "1050",
"gpu-fan" : "40-100",
"gpu-memclock" : "1450",
"gpu-powertune" : "50",
"intensity" : "22",
"temp-target" : "90",
"temp-overheat" : "93",
"temp-cutoff" : "97",
"vectors" : "1",
"worksize" : "256",
"lookup-gap" : "2",
"thread-concurrency" : "27400"
}