[header] How to change between tower and desktop orientations in a compaq evo tower [title] Remove the access panel. [step] On the back of the computer, use a screwdriver to remove the two screws that hold the access panel in place, then slide and lift it away from you. [title] Remove the front panel. 
[step] Press in on the two plastic tabs which are next to the underlying green arrows, then rotate it away from you and lift it out. [title] Rotate the cd and floppy drives to the horizontal orientation.