My understanding is that the board and 2U heatsink will fit into a 2U chassis and if I had fans in the chassis to force airflow over the board and CPU, any excess heat will be disbursed and later be extracted by the rack fans.
While there is no aircon where the rack is located, the rack itself (NetShelter CX 24U) has extraction fans. The servers will also be 1U apart which should allow for more airflow and heat disbursement.
That said, would it be better to invest in a 3U or 4U chassis? It does seem like waisted space, which could be used for a shelf (I have a ton of single board computers I need to fit in too).
I have a Talos II with dual CPU's, each CPU with a 3U HSF. Therefore a 4U tower/workstation chassis was a natural option for me. I'm currently in the process of replacing the PSU's, which isn't as simple as I expected. I'm replacing the redundant pair of PWS-1K41P-SQ PSU's with a pair of PWS-1K28R-SQ PSU's. I was expecting a simply swap-out replacement but I suspect the firmware in the machine needs updating. I'll keep the community and HCL on the wiki updated as to my progress (I've already added a note to the HCL:
https://wiki.raptorcs.com/wiki/Talos_II/Hardware_Compatibility_List#Problematic_Cases ).
Moving forward -- in addition to ensuring that firmware is not the concern -- I also intend to reproduce a few other people's research. I'm specifically interested in recreating hardware+firmware testing environments, reproducing other tests, and interpreting the results as applied to my own Talos II.
If I were choosing to create a remote workstation or server then I would probably use one of the SC846 series and keep the 3U HSF's. Inadequate cooling is one less issue I need to be dealing with at present. However I would be very careful about which PSU's and PDU's I select, and I would check and do research first. Several people Raptor and the Talos+Blackbird community have some very useful research about the characteristics of the voltage and current that various Supermicro PSU's supply.
Also the SC846 series of chassis seems to have something of a cult following and there is a lot of community knowledge about these chassis. Topics regarding airflow, noise, modifications to the backplane, have been well studied and experimented, by many people, in various homelab communities for development servers, or for experimental servers for research projects, or ..., etc.