The ornamental design for a clamp for attaching a computer game controller to a desktop, as shown and described.
FIG. 1 is an exploded right side perspective view of a clamp for attaching
a computer game controller to a desktop showing my new design, the broken
lines illustration of a steering wheel form no part of the claimed design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is an enlarged rear perspective view of the clamp arm thereof; and,
FIG. 4 is an enlarged top perspective view of the clamp handle thereof.