i anybody is interested i can provide these settings with all info you need for 0.04 btc
-270x 495 khash eating up to 190w tested in 4 gpu rig stable for a 24h
-7950 705 khash eating up to 230w and is also stable but these card can be pushed up to 725 khash but then they are not much stable and eat more power
with 270x its easy and difference in hashpower is within 5 khash between models .. but if you have 7950 with good cooling you can get probably those 725khash stable but for me must be enough 705 :-/
pm me if anyone interested