These are my settings for Gugabyte R9 270
non-x giving me just above 180 khs, 0% reject, 0 HW, do far, 20+ mins:
"intensity" : "12",
"gpu-threads" : "2",
"worksize" : "256",
"lookup-gap" : "2",
"thread-concurrency" : "4448",
"vectors" : "1",
"gpu-engine" : "1050",
"gpu-memclock" : "1500",
"gpu-fan" : "70-100",
"temp-target" : "70",
"temp-overheat" : "75",
"temp-cutoff" : "80"
Hope this helps anyone.
Edit: these settings seems not to work :\ The whole windows froze up.