Thanks for the tips Rablack,
I'm cutting on all sides air holes with a nice grill to keep it cool I hope.
I did use for my Popeye project a extra fan, because there was not much airflow and the temp was raising sky high without it.
On this one there is already an fan on the cooling strip, and the airflow I hope, with the design I have in mind, will be ok.
This time I did use the original bottom of the xbox with the metal under the board, so I can attach it very easy to the mdf, so I hope the sound issue will not be the case.

That's whey I had that little noise bug when I build the Popeye
The heating problem with the power supply is also my concern

I was thinking about using the original metal from the old casing, but I'm afraid of some contact with parts of the cpu and motherboard ... or I protect the buttons in a way that comes in mind
Always a challenge to fix problems when it's time to finish things up.
I use Vision with not the eye candy stuff like Hyperpsin. I like the way I did it with the Popeye build more.

why do I always ref to my prev. builds

It gives you more a console feel than the coinops bulk look