This type of case definitely need a fan. I didn’t know what was the safe temperature for two days. Last Sunday evening my Parallella box stopped working. Apparently it had been exposed to excessive heat well over the safe limit for several hours. I haven’t decided yet to buy another Parallella unit.
It was first time of completely destroying a system since I played with IBM AT computer in 1990. 😦
The board mounting hole take a 3 mm bolt.
I cut two steel plates whose thickness are 2 mm, drilled four 6 mm holes, four 3 mm holes.