Need Config Review & Some Questions

Budget: ~$4000

Expectations:
Fast reads/writes for patching/updating software & accessing/writing data, ability to multi-task without system bottlenecks.
Usage:
Iray Rendering in Daz3D 4.10(non-animation), Gaming, Multi-tasking. Monitor: 1440p Gsync.

Special Needs:
In the future, I'll be adding another GTX 1080 Ti to the system(in non-SLI configuration).

Saved Ticket #: 2087736

Specifications:

I'm thinking about changing the CPU cooler to either a Hydro Series H80i v2 High Performance Liquid CPU Cooler, or a Hydro Series H75(2018) Liquid CPU Cooler. They would have to be special ordered. Are these particular coolers sufficient for a Stage 1 OC? Or am I better off just getting one of the Corsair coolers with the bigger radiators that they offer here? My main concern is both noise & case heat, especially if & when I add an additional 1080 Ti.

When I install a second 1080 Ti later on, will there be sufficient distance between the two cards to avoid heat issues?

I was looking at the Velox due to having excellent airflow, but the thing I like about the Slade is less noise and being able to keep dust buildup to a minimum within the case.

Also, any particular brand or version of GTX 1080 Ti I should request? It's going to be under heavy use for sure, especially during the longer renderings. I've seen some versions with a higher clock speed come with 2-3 fans, which does mean more noise, but I'm fairly certain the clock speeds can be lowered manually.