Usually the front panel audio cable has two connectors on it; HD audio and the legacy AC '97 connectors. You should be using the HD audio connector. Be sure you have the connector oriented the correct way so that the dummy/empty pin is in the right spot. Most connectors have no hole there and won't allow you to plug it in wrong, but check to be sure. And check the settings in the Realtek driver control panel to see if the front jacks show up. Do both the headphones and the mic not work, or just one of them?