A personal computer chassis having increased reliability, versatility and decreased manufacturing costs. In a first embodiment, a disk drive is installed in the chassis in a first orientation for resting the computer on a desk top or in a second orientation, rotated 90 degrees from the first orientation, for resting the computer on a floor. The chassis is configured to allow interchangeable trim plates. When the trim plate is used as a base plate it has a larger periphery than when used as a side trim plate. In a second embodiment, a disk drive may be installed in the chassis without screws. Spring urged clips allow the disk drive to be easily inserted into the computer chassis, yet provide secure attachment. In a third embodiment, electrical contact is ensured for input/output port covers attached to the rear of the computer chassis. Each cover is made to bend slightly over protrusions on the computer chassis, forcing the cover into firm contact with the protrusions. In a fourth embodiment, a cooling fan housing is attached to the computer chassis without screws. Protrusions on the fan housing engage apertures in the computer chassis such that the fan housing easily snaps into place and is securely held. In a fifth embodiment, standoffs are inserted into the computer chassis through rectangular holes. Each rectangular hole has bumps in its interior which secure the standoff against rotating when tightening or loosening a screw. In a sixth embodiment, a security loop allows for attachment of a locking device to secure the computer against theft. In a first position, the security loop is extended. In a second position, the security loop is rotated flat against the computer chassis.