Now i have set it to GPU voltage 0.993V @ 1080Mhz and mem 1.5v @ 155Mhz with this settings in cgminer -g 1 -w 256 -I 10 i get 555Mh/s ,if i set the I to 13 i get 575Mh/s , in scrypt with the right settings i have mined with 620Kh/s, but this is enough for me i have aside this an Sapphire Dual-x HD7870 Xt (has core voltage unlocked , i have set it to 1.01V and 1070Mhz core , 155Mhz mem,same settings in cg miner as 7950 and i get ~470Mh/s  ) ,i mine with both at 1025Mh/s with 385Watt/hr power consumption @ wall.