Some of these results are not making sense at all.
I have tweaked my Asus RX580 (8GB) according to best guide and not getting over 1000 hash on each.
I dont think its possible unless you having clocked it to have hundreds of memory errors and card then fuck up..
So! If you don't know how to do it then it is impossible?
Didnt say its impossible, just saying with the dodgy overlocks your not considering power draw.
Considering the safety of your cards, then good luck with your power bill vs profit of mining.
Good luck with the life of your cards..