Sound has clicking/crackling noises! (ASUS PB5 Deluxe mobo)

After building my pc and putting XP on i ran the Asus disc and installed the Sound Max drivers. The pc ran with np's untill i played BF2 and 2142, i noticed that various sound effects most notably explosions gave off clicking or crackling sounds?!

Ive also noticed it in music and whilst watching movies etc on my pc.

Now ive checked the driver date for my on-board sound and it's from last august, so i decided to visit the Asus site and dl the latest drivers. It was only till i'd installed that i'd noticed that the drivers were the same as the one's i had installed from the disc, oh well :)

Atm im running 2 d/top speakers into the audio-in connector.

Any idea's guys?

possibly too high volume? I have the same thing when playing music on winamp and increasing the db outage to +20 on my laptop

Ok thx!

Yeah my volume is maxed out as the volume from the speakers is pretty low compared to how it was when i used Realtek onboard sound on my ASRock mobo.