Impotent fury at being unable to untangle cables, wires, chains or rope like items.
John had cable rage, his power supplies were tangled.. And in order to free them of his audio equipment wires he risked pulling his computer off of his desk. The computer mouse and keyboard had already fallen off the desk, hitting his head and back and he is hoping they aren't broken or have any buttons missing. But he knows he cannot lash out, with so many valuable items at risk. This is cable rage, a lonely, frustration driven madness.