Wow, didnt know that its so featurerich... and all 4! power connectors are for cables that goes horizontal right? The left 3 for sure but im not sure with the right one. But i guess the second right one would be the one to use with a ATX-PSU.
Do you mean the green power connector goes with ATX? I wonder how to split power from ATX to multiple boards, like 14? What additional cables/connectors do we need?
You would most probably split the power from a psu via y-cables.
Putting a heat sink on top will restrict the airflow over the pcb. The pcb has internal copper layers ('ground' is usually designed as a plane) which act as heat spreaders as well.
Do you say the other side of the pcb needs airflow too? I intended to force the airflow from the fans through the heatsinks only to maximize cooling. Do i have to rethink this?
The chips are designed to release heat out of the bottom, and putting a heatsink on the top of the chips can restrict convection and cause the chips to overheat. The top of the board doesn't need additional air flow AFAIK. The fan on the heatsink should create enough airflow around the board that all you need on top is convection for the other parts. That is, don't cover it up, but no need for anything else.
So it doesnt need airflow but then you say the fan will make enough air. But what will happen when i force the airflow ONLY through the heatsink. You know like creating a tunnel. I would like to take 2 miners with heatsink and put them together tight with the heatsinks. Then put a fan on the side and somehow build a tunnel that only allows the air flowing between the ribs of the heatsinks. Im not sure yet what material would be best for this but i think it would greatly effect the cooling because i think otherwise most of the air is going useless the easier way.
So would that be possible or is it needed to put a little bit of the airflow to flow above the other sides of the boards.
I believe convection is enough for the top of the board. Just don't plaster over it or cover it with a blanket.
I think the question is if a bottom side heatsink is enough for strong oc.
Maybe its a good idea to use a (bit more expensive) heatsink with a lot of more fins/surface and a 80/92 mm fan for each unit + top side heatsink (w or w/o fan). sandwiched.
should be enough for 70 W.air cooling is much cheaper than water cooling.
I NEED these! 
