Cooling device with liquid for electronic cards, in particular for high-performance processing units, comprising at least a hydraulic circuit in which a heat-carrying fluid flows in order to extract the heat produced by electronic components and/or hot spots present on an associated electronic card. The device comprises a cooling plate mechanically coupled to the electronic card so as to be inserted in a containing rack of the processing unit. The plate has a heat extraction surface facing and partly in contact, or at least in close proximity, with the electronic components and/or the hot spots. The hydraulic circuit is made in the thickness of the plate and has a geometric grid development, along which a plurality of hydraulic sub-circuits are disposed and switching means to define desired paths. The plate has sliding guide means able to cooperate with corresponding alignment means of the containing rack.