I've seen some videos/pics around the internet where guys can set this option as high as 16GB.

In my B450M S2H rev.1.0 bios (F61a), the highest option I have is just 2GB!

I do have a particular interest into pushing this setting up to 6GB or even 8GB. Does anyone know or can point me towards the right place to be able to achieve such goal?

Maybe downgrading or giving a modded bios? Any positive input towards these particular goal will help!