Electronic device for liquid immersion cooling

An electronic device that is immersed in a coolant filled in a cooling apparatus, and directly cooled, the electronic device being configured to be housed in a housing part of the cooling apparatus, and comprising a pair of substrate groups, wherein:

• each of the substrate groups includes a first circuit board having at least one processor and a plurality of main memories being mounted onto one surface of the board, a plurality of coprocessors, each having a housing with a rectangular cross-section, and an electric connection terminal, and a connector for electric connection between the first circuit board and the coprocessors;
• a distance H1 between the one surface of the first circuit board and a housing bottom surface of each of the coprocessors, upon insertion of each of the electric connection terminals of the coprocessors into the connector is longer than a height of the processor and each height of the main memories;
• and
• the pair of substrate groups are combined while having the first circuit boards arranged at a rear surface side in a direction for reducing a distance H2 between the one surface of the first circuit board of one of the substrate groups and a housing upper surface of each of the coprocessors of the other of the substrate groups.