have you compared your settings with the mining hardware comparison wiki?
https://litecoin.info/Mining_hardware_comparison

I see this settings for a sapphire 7950 11196-00

type                  KH/s     core   mem     volt                    version               settings

7950, 11196-00    650    1075    1250    0.962 U       cgminer 3.2.1    -I 20 -w 256 --thread-concurrency 24000   


greets