Try guiminer for 290 if all else fails, i had trouble with cgminer and sgminer running this card, especially thread concurrency. Something to do with AMD driver on new non reference cards.
I was using that first hour i started mining and it wasn't any good imo, Thanks though.
Are you still using Guiminer ? Because i can help getting CGMiner working if you like.
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[P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
GPU 0: 54.0C | 840.2K/839.8Kh/s | A:608256 R:1024 HW:0 WU: 765.8/m I:18
GPU 1: 54.0C | 895.5K/893.7Kh/s | A:603136 R:4096 HW:0 WU: 767.1/m I:18
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"no-restart" : true,
"api-listen" : true,
"intensity" : "18",
"vectors" : "1",
"worksize" : "512",
"kernel" : "scrypt",
"auto-fan" : true,
"temp-cutoff" : "81",
"temp-overheat" : "76",
"temp-target" : "71",
"expiry" : "15",
"gpu-dyninterval" : "7",
"log" : "5",
"queue" : "1",
"retry-pause" : "5",
"scan-time" : "15",
"scrypt" : true,
"temp-hysteresis" : "3",
"shaders" : "2816",
"thread-concurrency" : "32765",
"gpu-thread" : "1",
"gpu-engine" : "1000,1050",
"sharethreads" : "32",
"lookup-gap" : "2",
"gpu-powertune" : "20",
"gpu-memclock" : "1500"
Thanks a lot for sharing your set up, I tried 15 scan and 15 expiry but it gave me poor results. Just curious , How many shares per min are you getting ? Because you have more or less exactly the same setup as mine, I have two Sapphires.
For the Sapphire R9 290, I only need to specify threads 32765, gpu memory 1350 and I get 880H/s. Changing core clock makes no difference over time (and you SICK/DEAD if you go too high).
It doesn't like memory 1500 much ether, some cards lock up after a while. 1425 gives 890KH/s but 1350 has been rock solid (1% less KH/s and a good night's sleep vs 1% more and checking all the time...hmmmm

).
I've not had a problem with sick or dead, I've had them clocked at 1000 core 1500 memory for weeks and they never gave an issue like that.
How many shares per min you getting each card ?