The ornamental design for the back portion of a computerhousing, as shown and described.
FIG. 1 is an elevational view of a back portion of a computer housing
wherein the top section of the panel is defined by broken lines;
FIG. 2 is an enlarged fragmentary view thereof wherein broken lines are
used to define the top section of the panel as in FIG. 1; and,
FIG. 3 is a perspective view thereof.
The housing of the computer and the circles that are shown in broken lines
in the figures are for illustrative purposes only and form no part of the
claimed design.