That Netgear dumb switch? We've got 10-20 of those running 24/7 in user office spaces; they're all cool to the touch because they do practically nothing. Jam them into a tight, hidden space and safely forget about them forever.
The Zynq generates quite a bit, but the Epiphany very little. I've got a case kit for mine with a 0.4 watt fan, and that fan is total overkill for a single Parallella.