Extraordinary Sound Problem ( CPU related!)

Well, my system specs are in my sig but I will list them anyway:

Asus P6T
Corei7 @4.0Ghz
12GB Corsair DDR3
2X58701GB
X-FI Fatality Pro Gamer sound card
Zalman 850W
120GB OCZ Vertex Turbo SSD



Well, here is my problem: I am getting severe crackling/popping which eventually leads to no sound at all (after 30-45 seconds of crackling). (The sound will come back if I exit out of the application, and sit at desktop for a few minutes) Now I know there is a known issue with X-FI sound cards and crackling, however I have owned this card for almost 3 years and have never run into any problems even remotely similar to this.

Also, after switching to onboard audio to test if my sound card was good or bad, I still got the popping and crackling although, not as much. So this tells me there is a larger underlying problem.

Now, I only get this issue when running certain games, such as Operatio Flashpoint 2, Risen, and a few other games. I do not get this issue when running less demanding apps, such as a media player or Zune software, also games like Counter Strike show no issues at all.

The problems started shortly after I installed my 2x ATI 5870's. Which led me to beleive that there was some kind of IRQ conflict between the vid cards and the sound cards. To test this I just did a fresh install of Windows 7 64 bit, however the problem came back just the same.

Here is where I think this problem may be CPU related: I reduced my corei7 to stock 2.66Ghz and so far (a few hours of testing) I have had no sound issues, then I bumped it up a bit to 3.33Ghz (still no sound issues as of yet)

If after a few days of gaming with no issues, can I safely say that my CPU overclock is somehow starving badwidth to the sound card in my PCI slot ? Is this even possible ?

Is it possible that my 2 5870's are stealing resources from my CPU, if so, why does slowing down my cpu SEEM to fix the problem ??

It seems like games that are more demanding on my system are more likely to make the sound issues appear, what does this mean ?

I am really at a loss right now, and I need some very professional input into this situation. Thank you for looking, please help me!!!

Try taking out the Xfi entirly during the test; simply being installed and running (even if not used) can effect the output. Could also be the result of the OC.

Ahhh, but today for the first time since I downclocked my CPU it started doing it again, I am thinking it may not be CPU clock related afterall...

Actually, I bought my two 5870's at the same time, so I never had just one installed, it might be a good idea to test them one at a time and see what happens.