The motherboard manual for my VIA board cautioned that proper airflow is a requirement for fanless.

So I have the board in a vertical mount, with lots of case holes above/below the board to allow a chimney effect to circulate fresh air across the heat sinks.

The hard drive is, of course, mounted at the bottom of the case, below all of the heat-generating components. A modern notebook drive only gives off 1-2W of heat, so it will self-cool so long as nothing else interferes.

Cheers