First forum post, just to say I'm also experiencing sound loop crashes (albeit with a frozen picture, not a black screen). I'm running:

Q6600 @ 3GHz
4GB PC5300 Crucial Ballistix
Gigabyte DS3P-965P
BFG 8800GTS 640MB OC on 69.25 drivers (WHQL)
X-Fi Fatality (6.0.1.1304)
Triplehead2Go Digital
Vista Ultimate x64

The crash usually occurs within about 1-2 laps, and if I don't quickly hit CTRL-ALT-DEL then I end up with a BSOD.

If it's the overclock it isn't temperature related, 3GHz is actually pretty low for the 95W Q6600's (no reason to push further and probably RAM-limited anyway). I may revert to stock speeds to troubleshoot, but I suspect sound/graphics so will play with those drivers first.