Sound in games?

Hello, I originally had this in the Sound card forum but after further insight this seems like the place I should have put it.

I've recently built my first computer with a friend, and we've installed everything correctly, I've done everything I can think of to solve this issue (Updating drivers, settings etc) but I can't for the life of me figure out what is causing this crackle during games.

System info
Windows 7 Home premium 64
6gb ram
i5 [email protected]
9800GT
ASUS P7P55D LE Motherboard

Basically, whenever it seems like there is too much going, which is generally not a lot, the game seems to lag slightly and then the sound starts to crack and pop in the headset that I am using. It shouldn't be the headset as it was working fine on my older computer not 2 days before hand.

I've updated the MB chipset + audio drivers, updated my headsets drivers, uninstalled and reinstalled the games I've played where I get this issue but nothing has worked.

Also, not sure if this is related to that, but I also use Ventrilo while playing WoW, and I often get a delay on Vent when I press my Push to talk key and the program picking it up. Often I'll push it once, not hear the bind noise, so I'll push it again and then I'll have the noise play twice.

Any help would be greatly appreciative, I am at my wits end.

If I have missed anything for my computer specs, please let me know so I can rectify it!