A rack assembly (10, 20, 30, 40) comprising: a cooling module (108, 108') for liquid-to-liquid cooling; a rack (200, 200'A-200'N) comprising: a rack cooling block (118A-118N, 118'A-118'N) configured to cool a rack electronic processing assembly (120A-120N, 120'A-120'N) when the rack electronic processing assembly is placed in contact with the rack cooling block; and, a rack fluid conduit (103, 103') configured to circulate a first cooling fluid through the rack cooling block and the cooling module; and, an immersion cooling rack (300, 300') comprising: a dielectric immersion cooling fluid (124, 124'); an IC cooling block (126A-126N, 126'A-126'N) immersed in the dielectric immersion cooling fluid and configured to cool an IC electronic processing assembly (128A-128N, 128'A-128'N) when the IC electronic processing assembly is placed in contact with the IC cooling block; and, an IC fluid conduit (105, 105') configured to circulate a second cooling fluid through the IC cooling block and the cooling module; wherein the rack and the immersion cooling rack are thermally connected via the cooling module such that thermal energy can be transferred between the IC fluid conduit and the rack fluid conduit within the cooling module. a cooling module (108, 108') for liquid-to-liquid cooling; a rack (200, 200'A-200'N) comprising: a rack cooling block (118A-118N, 118'A-118'N) configured to cool a rack electronic processing assembly (120A-120N, 120'A-120'N) when the rack electronic processing assembly is placed in contact with the rack cooling block; and, a rack fluid conduit (103, 103') configured to circulate a first cooling fluid through the rack cooling block and the cooling module; and, a rack cooling block (118A-118N, 118'A-118'N) configured to cool a rack electronic processing assembly (120A-120N, 120'A-120'N) when the rack electronic processing assembly is placed in contact with the rack cooling block; and, a rack fluid conduit (103, 103') configured to circulate a first cooling fluid through the rack cooling block and the cooling module; and, an immersion cooling rack (300, 300') comprising: a dielectric immersion cooling fluid (124, 124'); an IC cooling block (126A-126N, 126'A-126'N) immersed in the dielectric immersion cooling fluid and configured to cool an IC electronic processing assembly (128A-128N, 128'A-128'N) when the IC electronic processing assembly is placed in contact with the IC cooling block; and, an IC fluid conduit (105, 105') configured to circulate a second cooling fluid through the IC cooling block and the cooling module; a dielectric immersion cooling fluid (124, 124'); an IC cooling block (126A-126N, 126'A-126'N) immersed in the dielectric immersion cooling fluid and configured to cool an IC electronic processing assembly (128A-128N, 128'A-128'N) when the IC electronic processing assembly is placed in contact with the IC cooling block; and, an IC fluid conduit (105, 105') configured to circulate a second cooling fluid through the IC cooling block and the cooling module; wherein the rack and the immersion cooling rack are thermally connected via the cooling module such that thermal energy can be transferred between the IC fluid conduit and the rack fluid conduit within the cooling module.