The ornamental design for the computer back panel portion, as shown and described.
FIG. 1 is an isometric view of a computer back panel portion showing my new
design;
FIG. 2 is an enlarged isometric view thereof; and,
FIG. 3 is an isometric view thereof.
The desktop computer system in FIG. 1 and the mini tower computer system in
FIG. 3 are shown in broken lines for illustrative purposes only and form
no part of the claimed design.