A computing unit configured to be mounted in a HPC cabinet, the computing unit comprising an external body, and an internal body comprising secondary electronic components. The internal body is releasably coupled with the external body in order to allow extraction of the internal body when the external body is secured fixedly to the HPC cabinet. The internal body includes a bottom tray, comprising bottom secondary electronic components, a top tray comprising at least one duct for conducting an air flow from the front to the rear, and a plurality of manual coupling members, accessible from the top of the top tray, releasably coupling the top tray with the bottom tray.