I think you are referring to the way the CPU is downclocking itself when not doing strenuous tasks such as gaming or video editing. Try playing a game (even a flash game might work) and monitor the CPU frequency in real time with CPU-Z. You should see the multiplier shoot up to 35 once the CPU needs the extra juice. Keep overclocking too, you could get at least 4.2 GHz out of that CPU, probably much more with adequete cooling and some practice.
I don't think I'm going to push it any higher than the 3.7 I put it up to, at least for now anyway. I have one of those self contained water cooling systems, but my cpu core temps on the cpuid hardware monitor are all around 90 degrees. I feel like I might need a better cooling system, but I've also seen that the 2500k's get really hot after overclocking.