Help with 3060 Mining

Hey im started mining ETH today with my 3060 and installed the beta driver that has no hashrate limit. I overclock the 3060 ( +1500MHz Memory Clock Power Limit 80%) when i apply the overclock in msi afterburner i get around 49-50 MH/s. But in like 4 minutes it drops down to 39 MH/s and i dont know why. As soon as i press the save button on msi afterburner again it instant goes up to 49-50MH/s. It seems like the overclock stops after like 3 minutes and i dont know why i only turn off my monitor but that isnt the problem cause when i let the monitor on for 3 Minutes it happens anyway. Maybe someone can help me