RX 470 ARMOR 8G OC max hashrate ?

hi there
i have been trying with this card RX 470 ARMOR 8G OC (samsung memory )
but i am not able to get any good stable values past 27.5mh/s

i set the straps of 1750 to 2000 cuz i dont have 1900
and the 1625 to 1700 and 2000
tried mem freq from 1925 to 2050
gpu on 1145 but it always uses less than 1100 on gpu

can any one help me get this card to 30mh/s without alot of incorect shares ?

thanks