I have a similar setup. NCASE M1 v6, Ryzen 7 5800X, Noctua U9S, but my GPU is an EVGA RTX 3080, so I don't have the hot air blowing through the card like the FE does.
The best temps I've managed are with the setup that [USER=3024]@rfarmer[/USER] has suggested. I'm using a Phanteks T30 on the side panel opposite the PSU, set to exhaust, and Noctua NF-A12x15 fans at the bottom as intake. I spent an entire weekend trying every fan in every location and orientation I could think of before I settled on this.
I don't think the U9S is up to the task of cooling the 5800X if you want to get the full performance out of it.
I've used the latest Ryzen Master software to auto undervolt my CPU, and I have fairly aggressive fan curves once the CPU exceeds 70 degrees, and it's louder than I would like.
Currently I do get better performance than I would from a Ryzen 5 5600X, but for an SFF build I would only use the U9S on a 65W CPU in the future.
Personally, I plan to install an EKWB 240mm AIO to get the more performance with less noise, but with my current work schedule that's only likely to happen in a few months. I'll post some info and measurements on the forums when I do make the change.
