It supports EATX - in the sense that EATX is ATX but deeper. Wendel at L1T did a build in one with a mildly EATX board, and it didn't encroach on the cable passthroughs much at all. Larger obviously would require more cable routing creativity.
I wasn't familiar with Wendell or Level1Techs but after some googling I found what you were referring to (the L1T abbreviation threw me for a loop)
Alright, so he built it with the Asrock X670E Taichi, which according to the manual is 12.0"x 10.5
is thus
ever so slightly larger at 12.2"x10.9". Will have to look at th efit in his build and try to guesstimate if it will fit. Can I make 5mm wider and 10mm longer work?
It's going to be VERY close...
Fractal Designs general case design philosophy seems very similar to how it was on the Define S years ago, in that there is a slope midway through the cable passthroughs:
If the motherboard fits to the left of that slope, all is good. If it doesn't, that's when we run into trouble.
I need 10 more mm than his X670E Tachi board, and I just can't tell from the video if I'll get it:
One way or another, it will be pretty **** close.
Side note: I was unfamilliar with this reviewer before, but I like him. He has many of my same priorities, including wanting more PCIe slots