Are nothing. Big diference from a generic shit to a good product.
About the tests:
Increasing RASMACACTWR to 69 and RASMACACTRD to 55 gaves me extra 20H/s. So, at 1150/1900 the RX470 is mining atr 938H/s. Yep, lowering tRC to 60 and TRCDW(A) to 13 gives me extra 4H/s, but I think the stability cost dont worth it.
Increasing RASMACACTWR in Elpida strap gaves me some hashes too. 946H/s at 1150/2020. It wasn't the goal, but good to see the Polaris shining. Nice

RX 470 : 1020 h/s , sgminer @1250 core, @2100 mem, 66W (gpu-z)
942 h/s , @1150 core, @2050 mem, 52W (gpu-z)
777000000000000022AA1C00AC615B3CA0550F142C8C1506006004007C041420CA8980A9020004C 01712262B612B3715