I would bet on motherboard - you missing only one slot - if you over/under tight (very easy without using included torque wrench) cpu you'll loose one channel - 2 slots.
One warning: right now international shipping is crazy. Couple months ago I have shipped PCB board aroun 5" x 5" (120 x 120mm) from Germany to US - 35 euro.
With a dimensions: on a "end view" you put 180mm dim on outside, how you'll fit 180mm fan inside? wall thickness? bend radius (where steel have advantage to aluminum - sharper bend radius) - or I 'm totaly wrong and fans are mounter on top of that bracket?? on "top" view - fan is 180mm square...
May ask how much you paid on Freelancer? I did check your drawing and you got a some mistakes on it, I hope it got corrected in CAD, and one more advice use steel not aluminum (magnetic, stronger and better for bending).
Well, you are wrong, look like the bug is heritage of multi-socket HCC Xeons, but you can easly fight it with CorePrio.
@spacedrone808 yes you can install Win7 on WX (2970 tested) Threadrippers.
Socket F came in both 3.5" and 4.1" distance. I used to have Noctua NH U12DO A3, on quad Opterons 6366HE, thanks to [H]ard bios pushed from 1.8GHz to ~ 2.9. Fully loaded with F@H in a open air, it was quiet enough to be in my bedroom.
Well, to disappoint you, that bug existing in Win7. I did testing today.
First is 1900X (rest of the system is not changed)in Win7:
and in Mint 19.1:
results are very close, but after 2970WX swap:
Win7...
Don't even think about DS380, unless you plan running it with 4 disks or heavy modding, it will be loud and boil your drives (even slow 5400 rpm disks) - very poor design of drive cage.
I did use same Asus card on my Asrock EP2C602 (with v2 Xeons) and it work correctly (all drives visible). Did you try different bifurcation setting? Maybe is mislabeled ...
Well, I have bad and good news. Bad news is, motherboard on previous screen shot crap out with new BIOSes for 3000 series. Basically it "killed" my W7 installation after couple restarts, but W7 wasn't alone: same way it treats W10, so consensus is Asrock B450 ITX motherboard can't handle 3000...
"4 hours later"...
I think that MC was "ravaged" @ BF :)
They listed before:
10+ 3900x's - gone
10+ 3600x's - gone
some 3800x's - gone
and even last 2920x is "missing" too...