Could try mounting test benches.

any examples of this you've seen? sounds interesting

What you're looking for is the Dimastech Test Bench.

http://shopusa.dimastech.com/dimastech-bench-test-tables


This one to be exact... http://shopusa.dimastech.com/dimastech-bench-test-table-easy-v30-graphite-black






This post was edited by Ghot on Jul 22 2019 11:57pm

Rotate the cases 90 degrees so the back of the motherboard (I/O plate) is pointing down at the floor and the cords come out of the "bottom". This would work on both walls. Wrap the cords in the same color material or use a tube / half tube to route them down the wall. With cable management I think the cords would look pretty similar on both computers. You're going to need some extra long cords to make this look nice.