Apparently you are mining from a country with low electricity. These cards at 250 watt consumption without BIOS modification and the almost 20 Mhash they give in a country like mine where electricity cost is 0.16 euro/kwatt surely its a suicide to mine with these cards. In fact if you check Ebay Italy you will find these cards being sold as cheap as 80-90 Euro so for some people who live in India or Iran where electricity is super cheap these maybe a really good option to mine but for Eurozone main countries no. I am happy at 90 watt and 24.1 Mhash mining ETC with GTX 1060 3GB.
Yeap, electricity cost in Estonia is low, so you don't really have to care with what you are mining with
But still, I really would want to up my hashrate over 20Mh/s
I would suggest to check a few tutorials of how to flash the Bios of your card/cards. Look for videos in Youtube and for step by step guides in google. They exist although they are more difficult to find compared to RX series which google and youtube is full of guides and videos where the RX series are being Bios modified. I would also suggest that some professional do it, a friend of yours would be perfect if you fear you might brick your cards and lack the expertise of such thing.