FAQ and MORE! 
Also got it compiled and all, but as soon as I put (gpu-threads : 2 )in my config, I get the following
Error -5: Enqueueing kernel onto command queue. (clEnqueueNDRangeKernel)
GPU 0 failure, disabling!
And using gpu-threads : 1 makes it run about 30% slower than it should...
It appears that with Scrypt-N You need to have at least same or more amount of system RAM as is on Your VGA, so If You have 2G of ram and some R9 VGA with 3G, Youll get this error with higher thread concurrency. Eg (approximates)
R9 280X w 3G video RAM + 2GB system RAM on scrypt with TC 8192: 700khs
R9 280X w 3G video RAM + 4GB system RAM on scrypt-n with TC 8192: 350khs
R9 280X w 3G video RAM + 2GB system RAM on scrypt-n with TC 8192: Error -5: Enqueueing kernel onto command queue. (clEnqueueNDRangeKernel)
R9 280X w 3G video RAM + 2GB system RAM on scrypt-n with TC 4096: 200khs
Will this work with normal Scrypt coins if I change it in the config from Scrypt-vert to just Scrypt? I love the raw intensity option. I have 2 280xs in an enclosed case that run well at I 13, but together are just too hot for the enclosure. I've had success with this miner setting them at TC and raw intensity 7168 which is essentially I 12.807. They stay at temps that I like and I'm fine with 87.5% throughput. However, if like to point one of them to a Scrypt coin and am not sure if there are other miners that allow for such fine tuning of intensity.
Coming soon I will post the guide with switching from scrypt to scrypt-n. For now its in developement and will require some time for testing/compiling."rawintensity" : "11264,11264,10240",
"worksize" : "256",
"lookup-gap" : "2,2,2",
"thread-concurrency" : "8192,8192,8192",
"temp-cutoff" : "90",
"expiry" : "30",
"log" : "5",
"gpu-engine" : "917,917,917",
"gpu-fan" : "90,90,90",
"gpu-memclock" : "1500,1500,1500",
"queue" : "0",
"shaders" : "2816,2816,2560",
"scan-time" : "1",
"device" : "0",
"scrypt-vert" : true
}
I'm getting 300kh on one of my 290x's right now with these settings... any suggestions/help?
I have 2 290x's and a 290, how do i get the miner to startup the other 2? just says "OFF" on the other 2 when i start
In order to run multiple gpu you must change "device" : "0", to "device" : "0,1,2" to run 3 GPUs. Can also run only certain GPUs if you prefer.
Also with most GPU thread concurrency ends up at 8193 rather then 8192 this can make a big difference (test BOTH)
Lastly 290x are much different then most gpu. As far as I can tell it can be easier just to go with single thread and intensity 20 and higher thread concurrency, all depends. When I get a collection of more good configs I will try to post more info. 
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