Hey everyone I'm looking to get a board like an ASRock B550 Phantom or the ASUS TUF of similar size then put it in a like case.  The plan is to have the ASUS' new APU in it for browsing and other basic things and a few others but when I want to stretch its legs I was hoping to pair it with a 3080 with an M2 adapter to do video encoding or gaming?  I plan on getting an appropriate PSU so my questions are will the 3080 get enough power out of the adapter?  If not I guess I stop here.  If I'm good there will the setup make it CPU bound?
I'd prefer not to make the case substantially bigger and rather create an enclosure with the M2 adapter as well as the PSU.

I'm more thinking about the high ceiling but if a case like that exists with the same small size maybe.  I would externalize the PSU obviously.

Your thoughts on my Mini PC concerns XrayMan?  Anything to add?
 
edit:  Checked most of these cases and the closest that comes to what I want is the Corsair 380T.  Just like I thought most Mini and MicroITX are too long.  I want a NUC sized case with a high ceiling so I can fit a full sized GPU in it along with honeycombs on both sides for good airflow.  No one makes a cases like this so the only other scenario is to buy a NUC case and make my setup modular with an m.2 adapter for the GPU.