Thank you. Yeah, I saw the connectors.
In addition there might be a fan and a heat sink above the processor and the RAMs.
Their overall height is probably at least 20mm... and some distance to the upper board the fan also needs to suck in air. But it has the advantage for me that a part of my board is in the intake flow of the fan.
At the moment I simply assume a distance of 30mm and for this distance there are still simple double row connectors.
(Translated from German by deepl.com)