I would use nothing but liquid cooling when over-clocking any component.
(Hey, I work in Saudi Arabia.
The majority of overclocked systems, including my four, use air cooling.
I haven't built an AMD system in years, so I do not know how well Cool 'n Quiet works. On my Intel systems, I turn off Speed Step, develop the OC settings, then reenable SpeedStep. Final test is small fft's (CPU) and blend tests (memory) for 24 hours each.
Stability is pretty important to me. Been doing this for a few years.
----------Overclocking since 1978 - Z80 (TRS-80) from 1.77 MHz to 2.01 MHz