ehmmm-... sry but you know that "-powlim 50" means +50 powerlimit which will break down every system.. all newbies will burnout his cards with this start settings.. im running my crads with -powlim -25 GPUmhz 1250 and Memclock 1100 and i get for each crad ~1.7Mhs  

EDIT:/ sry .. my rigs are running on vega64