Tell me best settings for xfx rx 470 4gig and rx 480 nitro 8gig. Not so good :/

ZEC - Total Speed: 706.005 H/s, Total Shares: 91, Rejected: 0, Time: 00:03
ZEC: GPU0 246.236 H/s, GPU1 233.392 H/s, GPU2 226.377 H/s