HP 6620 Win 7 Audio Breaks UP

I have a HP6620 desktop with Win 7. The audio from the rear audio output to a speaker system and the headset output from the front audio output both have audio that breaks up. The audio and video that streams from the pc to my smart tv is good. The device manager lists two High Definition Audio Devices and says they are working properly. How do I go about troubleshooting this problem? Does the Hi Def Audio Device mean I don't have an audio card or are they just drivers? Thanks for the help.

Thanks for the reply Firebred. It is an HP 6620f with a AMD Phenom II. Its just an off the shelf desktop but suits my use very well. I think I have got an idea what the problem is. If I shut down a lot of the cpu hungry programs it runs the music files just fine with no pauses or studdering. I probably have so many programs running those with a higher priority are demanding the cpu's attention and the Itunes and Realplayer are having to take a back seat. I will monitor for awhile. Thanks for your help.