An apparatus includes a heat receiving portion which receives heat within a footprint from a heat generating structure, and a cooling arrangement which causes flow of a coolant that absorbs heat at the heat receiving portion, the cooling arrangement being disposed in its entirety within a width of the footprint in a particular direction. A different feature involves an apparatus which includes a heat receiving portion at which a coolant receives heat, and a coolant separating portion which receives coolant traveling away from the heat receiving portion, and which separates liquid coolant from vapor coolant.