2 rx 570 mini 4gb Elpidia :
firstly bios mod - copied 1500 memory to the rest. to 1 and 2 segments
Should be ok. I typically copy the 1625 straps on a 470 card though.
Why? You don't want to increase you mv on GPU or memory. Or did you mean you changed your memory clock from 1000 MHz to 1950 MHz?
This is not doing what you think it's doing
and maximum 1975 in afterburner in memory
still i have got 27 m/h and second card less and millions of mem mistakes
what i do wrong?
If you are getting memory errors, then your memory clock is too high. If you are getting millions in a few minutes then it's way too high. Start dropping it by 50MHz, run it for about 5-10 minutes. If you are still in the millions, drop it another 50. If you are getting thousands of errors in 5-10 minutes then start dropping by 10 Mhz until you get Zero errors. You need to let it run for 5-10 minutes after each change to see if it's stable.
Every card will be different. You use Afterburner to find the sweet spot for each card, then burn that into the BIOS, so you don't have to depend on Afterburner.