Very glad to come here, hope to know more friends, hope to be able to help others solve some of the problems.Here, of course, you are also interested in the digital photo frame can also pay attention to my digitalframe8.
PC OS only use one playback hardware at time. Your PC has 2 playback hardware..External Soundcard and The Sound chip on the GPU card 5850. As stated on earlier recommendations...
Go Control Panel Select Sound Option On the Sound Option Selec "HDMI" as your default output.
You may need to reboot the PC if the sound don't transfer immediately. Its not supposed to be but i have seen this happen on some of my hardware.