Can I use my Gamecube component cable with my Wii system?
No. The Gamecube component cable only had output connections for VIDEO and then you had to still use your other composite cable in order to get AUDIO, which worked fine on most Gamecube systems since they had two A/V ports. The Wii only has one Multi-A/V port so if you were to use your Gamecube component cable, you couldn’t get any sound at all, and that’s assuming that the Gamecube component cable would work at all on the Wii.