R9 290 4 GB
microCoinMiner -w 64 -g 1 -I 18 --thread-concurrency 42000 --no-submit-stale --lookup-gap 3 --expiry 10 --scan-time 1 --queue 0
R9270X
microCoinMiner -w 256 -g 1 -I 16 --thread-concurrency 21568 --no-submit-stale --expiry 10 --gpu-memclock 1500 --gpu-engine 1100 --scan-time 1 --queue 0
0 HW errors with current n-factor
edit: Halibit, -i 12 is limit for me too, except with parameters above
I have all GPUs 7950 model.
Looks like some one gives little more with -w 64 -g 1, but I 12 is still max for me.
Any way all that was good conversation. I spent 30% for my el bill without hw errors.