The Lenovo ThinkCentre M90n-1 Nano IoT is a rugged but silent mini PC suited for IT deployments and enterprise use. Unfortunately, the little desktop's performance suffers under load, primarily because of thermal throttling.
https://www.notebookcheck.net/Lenovo-ThinkCentre-M90n-1-Nano-IoT-A-fanless-mini-PC-that-can-t-take-the-heat.450174.0.html