A cooled electronic system and cooling method are provided, where an electronics board having a plurality of electronic components mounted to the board is cooled by an apparatus which includes an immersion-cooled electronic component section and a conduction-cooled electronic component section. The immersion-cooled section includes an enclosure at least partially surrounding and forming a compartment about multiple electronic components of the electronic components mounted to the electronics board, and a fluid disposed within the compartment. The multiple electronic components are, at least in part, immersed within the fluid to facilitate immersion-cooling of those components. The conduction-cooled electronic component section includes at least one electronic component of the electronic components mounted to the electronics board, and the at least one electronic component is indirectly liquid-cooled, at least in part, via conduction of heat from the at least one electronic component.