These cards are so random! I've managed to get the Gigabyte RX580's up to around 890H/s. But the new MSI Armor 580's with uber mix strap 3.1 are only pushing 818 H/s!! I thought they would do much better.
This is a frustrating hobby!!
it does take some testing and patience to find the right mix for your rigs for sure. I was very lucky to get most of my rigs built back when MSI 470 4GB gaming GPUs were readily available for under $200. Now is a much dicier proposition due to severe shortages of most models/types of GPUs.
One thing i will mention is that there are many seasoned miners that avoid the MSI Armor series at all costs. The consensus is that while almost all other MSI cards are great for mining, the Armor line does not match up, not even for the slightly cheaper price say vs their gaming model. This is further proven out by the fact that those Armor cards always seem to be among the last in stock when the GPU supply chain has completely gone under.
Anyway, I also thing Armor come in 4GB max, and at this point, i would recommend not buying any more 4GB cards for mining. Much better to go at least 8GB, even if you are sticking with 570/580's. Much better for future proofing.