The invention relates to a heat exchanger (1), in particular for an over critical cooling circuit. Said heat exchanger comprises a block consisting of tubes (R) and ribs. A gaseous medium, in particular air, can flow over said ribs. A second medium, in particular a coolant, can flow through the tubes (R), which are arranged in at least four rows (1.1, 1.2, 1.3, 1.4, in particular in a cross-counter flow in relation to the gaseous medium.