Personally I would recommend Streacom FC5 Alpha, it comes with the hardware to properly conduct your cpu heat into the chassis. I did a lot of testing on it and the chassis itself can dissipate like over 200 watts (over the entire surface area). But I would only recommend going this way if there is no gpu or a very very weak gpu as it is not designed properly to operate with a GPU. Since the case does not come with hardware to also dissipate the GPU heat passively, any GPU waste heat will become completely trapped inside the case.
There is also a passive HDPlex case (H5) which does allow you to passively dissipate cpu+gpu but they have not updated the GPU hole pattern mounting in 3 years. Thus you can only use the gpu mounting hardware with GTX 1080 Pascal and older. But the mounting brackets are current for CPUs.
IN terms of Streacom vs. HDPlex, well, the hdplex case, while not being as beautiful of a design as Streacom on the outside, completely nailed it on the thermal interface side. Overengineered and can transfer hundreds of watts (more than this case can handle, by far).
By comparison, the thermal interface hardware on Streacom is garbage. It uses an aluminum plate and half the heatpipes.
If you want to use a case that isn't designed for passive cooling, it will need to be pretty large since the only real option is the Noctua NH-P1
[URL unfurl="true"]https://noctua.at/en/nh-p1[/URL]
There's a few open air (X-Proto) passive builds using the P1, seems to work decently.
[MEDIA=reddit]sffpc/comments/o8dhyo[/MEDIA]
