Sounds like you would be loosening the black connector at the end of each heatsink. Trim away the rim so the connector can free float in the opening. I would assume the rim obstructs the connector from freely moving about, and it will pinch the cables, both. Thus trim it. Now, when installing the heat sink, manually connect the black connector to the MB, and remember to do this whenever removing the heatsinks since the connectors are now dangling by the wires.