AnandTech reviews
Thermal pad aside, we don't understand Zotac's choices. Fanless PCs are cooled either with a heat sink case, or with a large internal heat sink in a mesh-laden case. Zotac went for a unique solution... that leaves much to be desired (especially considering the low 11.5W TDP). We do not recommend the ZBOX C-series.
Source: AnandTech