I'd be really worried about thermals. The cards are very close to each other for an open air case, I'd expect it would need a case and enough fans to create some air pressure.

There is some weird parts about mining rigs that I don't really agree with.

"pcie risers" - as the author pointed out mining rigs usually go for 1x PCIE risers through USB cause they don't care about bandwidth - but that doesn't mean you need to go for that as well, you could have gone for 16x PCIE risers just fine which is just a long ribbon cable usually shielded.

"mining rigs use crappy PSUs from alibaba" - you can use whatever PSU you want.