This would be funny if it wasn't so unsettling. ASRock doesn't recommend a 2.5" HDD for the fanless Beebox:
"
For Beebox N3000 series, it is not recommended to install 2.5” HDD. If you install the 2.5” HDD, please keep the Beebox series in a vertical position to ensure better cooling performance."
ASRock inability to properly take care of a 4W processor is sad. A potato would probably do a better job (we're serious about this). Fingers crossed for the upcoming Apollo Lake revision.
Source:
ASRock (PDF)
Update: ASRock tells us that the next Beebox will NOT be fanless (Apollo Lake lowest TDP is 6W).