This makes me miss the days when computers were ~12 watts and (basically) passively cooled. This would not be possible on any newer system. I'm also not counting the 1" fan on the back of the wii which was replaced by a heatsink.
Most RPi style single-board computers (SBC) are passively cooled. Some perform better with a heatsink, some heatsinks come with a fan, but (for most use cases) it's not really needed.
Passive cooling went away during the 80s/90s homecomputer -> PC transition. But modern tech has brought it back - provided you choose form factor & performance expectations appropriately (even though modern SBCs are crazy fast compared to Amiga or Atari ST era machines).
What you sir need is a Dell Wyse 5070. Passively cooled, four 64 bit cores, you can put up to 32Gb memory inside, two DP outputs and an M.2 SATA socket. 4-6 watts at idle and around 16 watts at full chat.
