Nope. It isn't an issue with cooling capacity, it is an issue with temperature. Phenom II scales predictably with temperatures. 50C gets you to ~4GHz, -50C gets you to 4.5GHz, -90C gets you to 5GHz, -190C gets you to ~6GHz. -240C gets you to ~6.5GHz.
A cascade capable of removing 500w @ -90C is still only going to get you ~5GHz, the CPU has impressive temperature scaling which is also it's downside for air/water overclocking.
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