A thermosiphon cooling assembly cools an electronic device with a conical condensing tube disposed about a curved central axis curving upwardly from a top of the evaporating unit to an upper distal end and a shroud disposed outward of an exterior surface of the condensing tube at the upper distal end extending axially along the central axis from the upper distal end to a lower edge spaced from the top defining an air opening. An air moving device moves air about the central axis within the shroud to the air opening. A plurality of condensing fins are disposed in the condensing tube and each condensing fin forms a pair of corners with an interior surface of the condensing tube and a wick material is disposed in each of the corners to return condensed vapor to the evaporating unit.