I have GALAX RTX 2060 Super with Micron memories, I tried tons of combinations and couldn’t go further of 37,5 MHs in Hive and 38,5 MHs in Windows (with afterburner). But I always tried 130 Power Limit and different values in Memory and Core, the GPU always draws around 90 W.
Then I tried what MarcioS suggested and used 180+ PL, and that makes the trick. It seems that with a low PL the GPU is unable to draw more power so you are limited to use higher Memory values. The max factory PL for my card is 200W so I think not going further than that may be safe. Anyway now the GPU is mining 42,2 MHS and using 112W, it never reaches the PL value.
My actual overclocking in HiveOS is:
Core: -400
Memory: 1800
Power Limit: 190
MHs: 42,2
May be that playing a bit with this values I can get some extra MHs, but increasing the PL makes the huge difference.
The information in this post was very useful, thank you all !