are these for sale?

5 x GPU rigs x 2 per chassis?

Nice - I wish my laser had enough power to cut steel, but I'm not baller enough to do oxygen assist.    The slats will definitely solve the problem, I tried a similar design before and had exactly the same problem, that's why I suspected why you mounted the fans the way you did.    Oh, and you're better off not cutting that spiral pattern out of the metal - not only will it reduce your cut costs dramatically, but I suspect you're loosing 5-10% of your fan performance by having them:

https://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/

All in all I think you did a great job on your build - definitely one of the most well thought out designs I've seen.

Very nice - I see you're a fan of 8020 as well!    What material are you using for your sides?  I use acrylic but primarily just because I have a laser cutter and it's one of the easiest materials to work with:


One suggestion you might consider - I experimented a fair bit with airflow, and if I'm interpreting things right you're pushing in on the bottom of the front and pulling out on the top of the back.  I tried a similar approach, but it ended up being less efficient, and the best was actually making the push and pull parallel to eachother, and just putting vent slats above the front of the inlet fans, so hot air can't get trapped in there.  If you put the vents above the exhaust, then it tends to short-circuit - but as you can see in my latest builds, I just opted for no back panels at all and use industrial tubeaxial fans.