"I wanted to get a fully fanless PC for quite a while, but when I saw that the newer energy efficient AMD laptop processors come with a halfway decent 760M iGPU and pack quite a bit of CPU punch, enough for older games, emulations and also CAD work I was sold on the idea and used an ASrock Industrial Box 4x4 7640u as basis for my own design.
It is a quality LED heat sink from Wakefield-Wette bought from Digikey and is rated for 33W convection based heat dissipation. From my experience, those specs are pretty accurate, it can handle the 28W TDP CPU pretty well."
Source: reddit