A few months ago, inspired by The Scooter Computer, I bought a fanless Intel Broadwell 5257u computer. I set it up as a Core OS Docker host, but quickly discovered that I didn't actually have much use for Docker or Core OS. Recently I tried to repurpose it as a low-end Windows 10 game box. That unfortunately ran into heat-related stability issues. Windows 10 worked fine as long as I didn't try playing 3D games. Playing 3D games like Counterstrike GO would crash after 10 to 15 minutes, with a very hot heat sink. Fiddling with BIOS settings and drivers didn't make a difference.
I guess the lesson to learn from this is, when buying a fanless computer, not to get the highest powered available CPU. Safer to get the lowest power CPU that meets your performance needs. Or just get a fan. :-P