Yeah I saw those leaks, but they werent as clear as i had hoped. The ones that fitted a 3090 FE in the case werent able to close the sidepannel because its just too big, and i think its due to the power connecter, if you look at the NCASE M1 V6 info subforum you can see someone posted a picture of him with a FE in there. You can clearly see how little room there is left for any sort of power connector. So you have to look into some other way to power that beast becasue i dont think the stock powersplitter that comes with the card is slim enough to fit in there.Looking at the teaser pic it does look like rear fill but obviously nothing's certain yet.
I have come across a 3090 in the case but nothing that's fully built in and pannels back on .... it's the front power that will be an issue.