No hdmi audio

You have to install the HDMI audio driver.

Also, when you are in Windows you have to change your Audio Device from your default (onboard or add-on card) to the HDMI version.

Most HDMI is pass-through from a movie (not all codecs supported) like Dolby 5.1. You won't get Windows sounds or Gaming sounds as the onboard audio is not in the loop.

My dad's laptop has HDMI output and it IS wired to the sound card so I can output HDMI video and sound though I STILL have to change the Audio Device from the onboard sound to "HDMI" audio (it's still using the onboard sound so really it's just disabling the speakers).

HDMI audio from computers is a big mess. They should have only allowed HDMI from computers if it worked perfectly.

I'm not 100% sure that what I've said applies to your motherboard but I'm 99.99% sure. In fact, since it's missing the driver I'm basically 100% sure.

(Your motherboard manual has the HDMI driver.)

Your best options for audio on an HDTV are:
1) VGA+ Stereo audio (for BluRay, there's a Slysoft that bypasses HDCP)
2) HDMI-> use a card like GTX275 that has SPDIF input and run the SPDIF output from an audio solution
3) Auzentech HomeTheater HD
4) Use an external receiver for the sound.

Here's how the HD3870 HDMI audio output works which is likely how your motherboard works as well:

1) supported audio is read from the DVD-Video
2) it's sent out the DVD-drive and ends up on the video card
3) it is still not processed and is sent out the HDMI output

What's crazy is that since you can't get HDMI sound from Windows, Games or unsupported audio tracks who would bother hooking a PC like this to their HDTV? If you can only get pass-through then you might as well just use a normal DVD player.

Yes. I'm right. I got this from your motherboard manual:

After installing the HDMI device, make sure the default device for sound playback is the
HDMI device. (The item name may differ from operating system. Refer to the figures
below for details.), and enter BIOS Setup, then set Graphics Display Mode to D-SUB/
HDMI under Advanced BIOS Features.
• Please note the HDMI audio output only supports AC3, DTS and 2-channel-LPCM
formats. (AC3 and DTS require the use of an external decoder for decoding.)
In Windows Vista, select Start>Control Panel>
Sound, select Realtek HDMI Output and then click
Set Default.