Try : cgminer.exe --scrypt -I 20 -g 1 -w 256 --lookup-gap 2 --temp-target 75 --auto-fan --temp-cutoff 90 --thread-concurrency 24000 --gpu-engine 1050 --gpu-memclock 1500 (if You see HW Errors set -I 18-19)
Thanks to yours settings I'm getting 700-705 kH/s!!! Any other setting fail to break 700...
Can I know what bios version u have on those cards? Any problem with temperature? And have you checked VRM temp? One more (
), what kH/s you obtain with that config?