Abstract: A computer housing comprising spaced, parallel side walls containing grooves for slidingly receiving cards and spaced, parallel top and bottom walls to which the side walls are secured to provide, in conjunction with the side walls, a card cage and an enclosure for removably receiving, respectively, cards and a fan module, the invention comprising means for assembling the side walls to the top and bottom walls preparatory to securing them, comprising jig means on the side walls and top and bottom walls adapted to be interengaged to support the component walls in precise assembled relation to each other for securing and means independent of the jig means for securing the assembled walls to each other while so held by said jig means and including devices to assist in inserting and removing the cards and for coupling and uncoupling the fan module to a source of power.