here is what you can do.
set all core clocks 1150 , then remove the DPM states ( core states and memory states ).
Then put all core voltages to 850 and memory controller voltages to 800. test if you can run the cards with 2090 or 2100 memory clock.
if they are all working correctly after these settings. you can try to lower the core voltage by 5 every step until some gpu crashes and then you increase it 5 and check again if its stable.