There are 2 different types of front panel audio jacks. AC97 and HDAudio. Sometimes the type of connector is labelled on the connector itself, sometimes not. And its usually the case that a yellow connector is HDAudio, but this isn't always the case either. Sometimes the FP Audio cable will have both connector types, you should look to see if yours does. Usually they are labelled if both are there. Can you post your motherboard, as well as the new case you bought?