Radeon R9 290X gets around 1000KHash/sec @ 360W = 2.71KHash/Watt

R9 290X Sweet Spot @1000KHz

CGminer.conf

{
“pools” : [
{
"url" : "stratum+tcp://coinotron.com:3334",
"user" : "<USER>.<WORKER>",
"pass" : "<PASS>"
},
{
"url" : "stratum+tcp://stratum.give-me-ltc.com:3333",
"user" : "<USER>.<WORKER>",
"pass" : "<PASS>"
}
],

“intensity” : “20″,
“vectors” : “1″,
“worksize” : “256″,
“lookup-gap” : “2″,
“thread-concurrency” : “33792″,
“gpu-engine” : “1025″,
“gpu-fan” : “40-100″,
“gpu-memclock” : “1350″,
“gpu-powertune” : “20″,
“temp-cutoff” : “99″,
“temp-overheat” : “95″,
“temp-target” : “90″,

“api-port” : “4028″,
“expiry” : “120″,
“failover-only” : true,
“gpu-threads” : “1″,

“log” : “5″,
“queue” : “1″,
“scan-time” : “60″,
“temp-hysteresis” : “3″,

“scrypt” : true,
“kernel” : “scrypt”,
“kernel-path” : “/usr/local/bin”
}