Theoretically, what's the smallest viable build for Ryzen 9800X3D & RTX 5090 FE? (Discussion)

I've been planning my new workstation for VFX and 3D rendering using ray-tracing in Blender but also for gaming in my free time (mostly sim-racing and story-driven action/RPGs). I'm not looking to get into custom loop water-cooling as of yet, so I'll stick to air-cooling or at most an all-in-one liquid cooler.

For VFX and 3D work, the 5090 is a no-brainer as it is the only GPU in the line-up with significant improvements in ground truth performance (but perhaps not price...). All that "AI-cores" and "AI-upscaling" nonsense have negligible benefits in this field. So it's either the 5090 or the 4090, if I can get a good deal.

The 9800X3D seems to be an excellent all-around CPU. Even for professional use, it seems to hold its own in applications like Blender, although rendering speed will mostly come down to the GPU anyway.

All that remains is finding a case to house these components and most importantly dissipate the 575W + 120W of heat. 🥵 I've narrowed it down to either the NCase M2 or the FormD T1 / NCase T1 but I am open to suggestions!

The NCase M2 seems the safest bet with the entirely flow-through design of the 5090, 280mm radiator support and plenty of air coolers that fit as well. But the question remains whether to invert the case or not, as inverting would shoot all the hot air directly into the table to potentially recirculate into the side-panels. The normal layout would limit the GPU's supply of cold air, so the feet must be raised at a minimum. But I don't know which in theory would perform the best.

I drew inspiration from this build by EIGA which is in the FormD T1 (the NCase T1 is also on the table, you can fight about which in the comments). The T1 being a sandwich layout case seems to conflict with the flow-through design of the 5090 as it would blow directly into the back of the motherboard and power supply. However, With the 5090 FE being just 2-slots thick, you could put the T1 in its 3-slot configuration and cool the CPU with something like a fan-swapped Thermalright AXP90-X47 with a fan-duct which seems to (just barely) be sufficient to cool the 9800X3D. That leaves a whole slot clearance for two Phanteks T30s to pull heat away from the GPU. Surely some undervolting and power limiting would improve thermals and noise further?

There's probably many cases I'm overlooking. If you have any suggestions or thoughts on the matter, please share!