No sound with Radeon HD 4670 1g

Here is my problem I hope that someone can help me. I recently installed a Radeon 4670 1g card to my pc. I have sound with my windows media player, but not during game play. When I do a test it says my speakers are working correctly beside of the hdmi icon in the sound tab. BUT I am not hearing the sound that it is displaying is there. AND like I said I still have all other sounds. I have went into BIOS and the audio onboard IS enabled. I have went through all the steps that came with my instal booklet which is to go under hardware and sounds, then to manage audio devices, and set the HDMI as the default. I still have no audio. If anyone knows what steps I need to take to get the audio to work under game play I would appreciate it greatly!