Personally, I’m thinking that if the 40-pin GPIO is put on the underside of the board, then that creates space for a wider (not necessarily taller) passively cooled heatsink on the top.
After my investigations in this thread, I’m quite convinced that the VIM2, at least can be passively cooled rather effectively (even with the VIM Heatsink), at an ambient temperature of about 23C.
Of course, placing anything above the heatsink obstructing the convective air flow, will render passive cooling infeasible…
Some Thoughts:
- A large aluminium heatsink may be more expensive to manufacture.
- Some people may consider it ugly.
- From my design background, I know its possible to make these things look cool.