An electronic device has a first case which houses a part of a liquid cooling system and mounted components, and a second case which houses the other part of the liquid cooling system. In one example, the second case houses and a display unit. In an all-in-one computer example, the second case may serve as the access lid. In the electronic device, the liquid cooling system has a pump which feeds cooling liquids a heat block which receives heat from an electronic component, a pipe which transfers heat from the liquid to a heat sink, and a tube which connects these parts with one another. The first case has a first board mounted with the electronic component over a part of the liquid cooling system. Methods of manufacturing electronic devices with such cooling systems also are disclosed.