yes, R9-290 and R9-290X are more difficult to be set.
I am testing with --thread-concurrency 8192 and --gpu-memclock 1250 directly inside sgminer.conf and it seems more stable then before... more tests will come out in the following hours...
I'll keep you informed
thread-concurrency doesn't affect much NIST5-performance (check the source code) I would not touch it. Play with thread-concurrency only bring you 1% more in my experience.
Important is delete all the *.bin file in sgminer-nist5 and set proper clock, intensity.
anyway, now I am running fine sph-sgminer_nist5 on my windows machines with R9-290 and R9-290X at double hashrate...
the secret is to set --thread-concurrency 8192 and gpu memclock at lowest possible value (--gpu-memclock 1250 or --gpu-memclock 1300)
on some R9-290 lowest gpu-memclock is 1250 and on other R9-290X it is 1300
I'm running memclock at 650 on all rigs, no difference in speed and saves a little power...