useing" --mining-threads 5" .The result is :
2014-Aug-09 13:26:55.940664 OpenCL simpleminer should be used 1 instance per GPU
! Changing to 1 mining thread.
try this recommendation by mbk himself
Start multiple instances having different --device parameters (--device 0, --device 1, etc).
Ok. That was the trick. Working now with 4 instances / 4 GPUs . THANKS