The Chromebox 3 mini PC sports a diminutive case, but supports gen 8 Intel Celeron Silver quad-core CPUs. The more advance PN40 and PB40 can accommodate CPUs up to Pentium Silver and feature cases that allow for easy upgrades.
https://www.notebookcheck.net/Asus-showcases-three-new-mini-PC-models.277360.0.html