Just bought 4 Zotac CI323 nano’s to set up a low energy proxmox cluster.
With only 12x12cm those machines are tiny, and they only require 7 watts.
Inside I do use 16GB RAM (officially 8GB only, but it works with low powere RAM) and with a 500GB SSD from Samsung.
Thus the Proxmox cluster has 16 cores at 1.6 to 2.08GHz and 64GB of RAM, with overall around 50Watts, when using the powersave governor in Linux.