hi guys, i have 2 x r9 280x sapphire dual-x and i want digg some vertcoin, but i have problem. I use cgminer from vertcoin.org and i have only 300kh/s.

My config:
export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1
cgminer --scrypt -o stratum+tcp://stratum.vertco.in:8080 -u x.x -p x -I 13 -w 256 -g 2 --thread-concurrency 8192 --gpu-engine 1042,1024 --gpu-memclock 1500 --gpu-powertune -20 --temp-target 75 --temp-overheat 85 --temp-cutoff 90 --auto-fan

First GPU have 290kh/s and second GPU have 10kh/s. What wrong with my rig?

Thanks for help.