@zawawa since you requested comparison. Here's some numbers from SRB
6 x RX580 4GB (Hynix + Elpidas) on Cryptonight Heavy does ~800 per card. They do 995 (Hynix) and 1030 H/s (Elpidas) on Cryptonight-V7.

Show me your config miner please! My rig 8x570 maximum 5700h/s to all, ~ 710h/s to one card. Config miner "intensity" : 45, "double_threads" : false.
4gb cards. I/W/T : 59/8/1 for Heavy.