NanoPi M3 grounding

Hello everybody. Im very new to mod mini Computers. 

Im a Cutting machine Operator and i build a Case for my Nanopi M3 out of
Aluminium at my CnC milling Maschine. I want to mount my board in this Alu
case on spacers out of plastic. But i ask myself if i need to ground the
board to this case?

I read many Forums about grounding pc cases but they wrote down to much
several opinions. So i ask it myself again after the tech Forums.

Thank everyone that take care about my Problem.

NNN

Because there are many things to consider.  

1) having a grounded metal case is good from a shielding point of view, if
there were components sensitive to mains hum or other external
interference. I had one problem with a large AC relay that interfered with
the USB on the mini2440.  Fixed the problem at source.

2) Maybe not good to have a grounded metal box "floating" around a work
environment, however that could be one way to find things that are NOT
properly grounded.

3) what do you ground the case to? Is there an external supply? Do you want
to nominate the supply negative as the ground connection.  Then what does
that get grounded to.  Etc.

4) potential problems with "ground loops".  Possibly more applicable to
audio or instrumentation equipment.

I would mount using plastic and see if you have any problems.  There is a
example of a metal case, to get proper heatsinking, I think on their new
forum.  See what he did.