That rig looks killer, man!
I wish I'd seen this earlier I'd have advised you that a 1600W PSU is really overkill for what you're doing. That's the sort of PSU you'd get for an old-school power-hungry tri-SLI or even Quad-Fire setup.
And those multi-GPU setups are honestly only good if you're a slave to benchmarking. I've had SLI and Crossfire a number of times, and it's really diminishing returns. Even though FPS is higher, you actually need more FPS to have it feel smooth than you do w/a single card. Then there's the hassle of it not always 'working' with both cards because AMD/NV doesn't make an SLI profile for a game. I've had to hack together profiles many times, or force profiles from older games to be used on a newer game, etc.
It's pretty much going the way of the Dodo for anyone but hardcore OC/ benchmarking types.
Ergo, with a single card setup, even with H2O cooling and an OC'd 2080ti and an OC'd processor, the MOST PSU you really need is a quality 850W unit. 750W would've even been fine, 850W gives you a ton of headroom.
Just sayin' I know it's done already and certainly not worth crying over.