Powercolor RX470 4gb hashrate

Hi guys, so I got a few units of Powercolor RX470 4gb with Hynix memory I had enabled compute mode, bios modded, and with oc setting of core 1180, 870mv, memory 2000, 850mv The hashrate I'm getting is between 10.5-11.3mh/s, meanwhile the MSI RX470 with Samsung memory can go up to 13mh/s++ Is the hashrate I'm getting normal?