you can look at the user's benchmarks:
https://gos.cx/bench?algo=lyra2z&chip=5
https://angrypool.com/bench?algo=lyra2z&chip=3

Try to stabilize it around 2000~2050MHZ, memory OC has no affect, and the core voltage on card are jumping to 1050mV on stock, I only need to raise the core voltage when going over 2025Mhz.