I'm experiencing the exact same problem here, only with DCS:World 1.2.0, flying the Ka-50. After a while, the sound crackles, cracks, turns completely off and comes back on again to more cackling. This continues even after DCS was shut down.
Interestingly, I've noticed the same when playing another graphically demanding game (Empire :Total War).
No overclocking of my ASUS board, though. Running on windows 7 64bit.
RedX, did you even find a cause/solution for this issue?