Cool N Quiet was essentially designed to save power and keep your fan speeds low, ultimately resulting in your processor staying cooler. But, I personally find it to be a nuisance more than anything. Having Cool N Quiet on will not increase life on your cpu. If anything it shortens the life span. By going through that many changes (i.e. Bus speed increasing and decreasing and the voltage going up and down) it can't be better for the cpu than keeping everything stable 100% of the time. Especially if you aren't OCing.
Aside from that, it sounds like you have a mobo issue. If you aren't that worried about the cool n quiet I would just disable it, otherwise you should RMA the board.
Hope this helps!