oh too soon, it gives invalid results 
flash bios 6950 to 6970 and use this config; 360 h/s xmr-stak drivers 14.4 // gpu: Cayman memory:1663
// compute units: 24
{ "index" : 1,
"intensity" : 874, "worksize" : 19,
"affine_to_cpu" : false, "strided_index" : 1, "mem_chunk" : 2,
"comp_mode" : true
},