I'm in the middle of a similar build, and I'm curious how you got 4 of those to work well right next to each other. Are they FE cards, or some other variant?
Interesting that FEs are working, I had heard that that configuration was problematic. Have you seen much thermal throttling with them butting up against each other? I was going to resign myself to one blower 1080Ti in slot 1 and then a 2080Ti in 2 and 4, but maybe I don't have to :-)