Hello,
the Soc+RAM couple is not cooled at all, so under heavy load the CPUs keep on throttling.
I’m considering adding a heatsink. I found this (sorry it’s in French) which is a set of laptop RAM heatsinks; 13mm x 12mm seems to be the right size.
I would also like to add a fan to dissipate the heat from the heatsink, but I’m not sure what fans are compatible with the connector found on the robotic board.
Any help or hint greatly appreciated 
The dragonboard 845 design left me feeling very disappointed. Especially when considering the extremely high price, combined with how much potential the platform has that is, frankly, wasted.
Unfortunately, you aren’t going to achieve adequate cooling with that design. Its a PoP configuration, which is supposed to implement cooling through the copper in the PCB. In a good design, like the dragonboards 410 and 820, you can just stick the board to a big heatsink with a thermal pad. In fact, if you look at the 410’s board, you can even see a big gold square on the bottom – that surface is there specifically for cooling.
With the 845, you have the CPU barricaded in. On one side you have the RAM blocking heat flow, and there are so many EM covers over the board, that you will never get heat out of it that way. Putting a heatsink on the RAM will help… a little. But with a CPU that powerful, you are going to find yourself quite disappointed no matter what you do.
I have jerry rigged a small 12v like so:
I am getting sustained, under load clocks at: 2.6G and 1.7G for Big and Small cores. This is as high it’ll go i guess. Also no heats-ink required, the base of the SoM works as a heat-sink as these SoCs are designed to dissipate heat through the BGA down to the PCB rather than up like regular PC CPUs.
I would very much like to try out the on-board fan header, let me work on that and see what fan fits, I’ll update our documentation accordingly.
