sapphire 7990 card minidg GPU problem ?

[hardk]

I have the following problem, my AMD ATI 7990 card GPU-s with same settings make a 150kh/s difference during work. I tried many things but in every settings this difference exists. I did not get any results with trying different settings. How could i bring the weaker GPU up to the same performance like the strong one ?


http://i37.photobucket.com/albums/e85/seekerseeker/7990_gpu_zps50f7c93a.jpg