I have recently built a PC with the following specs

ASUS A7N8X Deluxe motherboard
AMD AThlon XP2500+
512Mb PC2700 RAM
128Mb Radeon 9000Pro Gfx
60Gb IBM GXP120 HD
Internal ADSL modem
Win XP Home Edition (SP1)
All components have current drivers installed

I will cut to the chase.....

All performance fine except for sound during gameplay. MP3's, DVD's and game menu sound is all reproduced without glitches. Once the games begin (I only play 3 games - Half Life, Counterstrike and Battlefield 1942) at some point in time the sound will become crackly and distorted forcing me to restart the game and sometimes the whole computer. When the sound does become distorted I can exit to the game menus where the sound is fine and when I return to the game the distortion is still there!

I have tweaked every setting in windows I thought might help and the problem has not gone away. Is there anything I can do to stop this VERY annoying problem from happening anymore, or do I have to buy a sound card?

Any suggestions???
All help, as usual, is much appreciated :)

If you have already tried adjusting the sound adapter's acceleration and sample rate, and changed different settings in its software, then make sure the video card is fully inserted, shut down all unnecessary programs running in the background, and try different sound drivers.
If no luck, then reduce the video card's acceleration one notch.
If still no good, then borrow a sound card.

Mute all the sound controls like CD Audio, Microphone etc and leave Master Volume/Playback, Wave/MP3, MIDI/Synthesizer un mutted and then play the game. See if it works.

BTW,
Is your video card and the sound card sharing same IRQ?
You can check this from the device manager.

CuratoR.

Display Adapter IRQ is 19
Audio Codec Interface IRQ is 20

ASUS's website clearly states that the nForce reference drivers are not completely suitable for the A7N8X and that their own drivers are best. I have tried both without success!!

It could be that the onboard sound chip itself is defective. Or that the advanced sound options are screwed up on the driver or hardware level. Have you tried running your games in software sound mode or something like "miles 2D fast positional" (or whatever)?

Also, see if you can borrow a PCI sound card from someone.

i faced a similar prblem while playing MaxPayne..
try this.

Goto Start > Run
Type in Dxdiag
Goto Sounds tab, and bring the slider to No Acceleration.
{*]Restart.

Enjoy ! (hope)