Help: OC settings for Kawpow

I'm new to mining and I my setup is:

2x RX 580 8GB (XFX OC+) 2x RX 5600 XT (Asus ROG OC)

Asrock Z77 Extreme 4 Intel i5-3570K 32GB RAM 850W Gold PSU Windows 10 AMD Driver version 21.1.1

My settings so far:

-580 setting / GPU-Z Shows: Core 1360 / 1360 Memory 2000 / 1999 Voltage 980 / 950 Getting 10-11.5MH at 130W – 65C Stock "Mining" BIOS

-5600xt setting / GPU-Z Shows: Core 1800 / 1740 Memory 1800 / 1740 Voltage 900 / 900 Getting 14-16MH at 130W – 60C Stock BIOS

The settings above are not much stable, and yet anything beyond these will cause immediate crash/freeze.

What are good hashrates for my cards? I saw some people getting ~2-3MH more on each similar GPU. And how can I get more stable and efficient? I'm not sure how/if a BIOS mod is going to help.

I'm a beginner so any help will be much appreciated.

Side note: Isn't it more practical for my case to mine ETH and then convert it to RVN? Since I have AMD cards and it seems more efficient that way.