I hate to be the bearer of bad news, but it looks like it won't work. The PSU itself isn't an issue, but the ATX bracket attaches directly to the frame, so there's only 1.5mm between the bracket and the side panel. That wouldn't be a problem, except for the fact the bottom of the bracket overlaps the top of the window by about 2.5mm.
Sorry guys, I should've checked this for conflicts. I wasn't that interested in doing the window in the first place, so I pretty much let w360 do it by himself. He isn't as intimately familiar with the design of the M1 as I am, so I can't really expect him to think of everything I would. The M1 is my work, and it's my responsibility to ensure that everything works the way it should.
Don't beat yourself up.
Why weren't you interested in the window? Didn't meet your design goals or what?