I gotta agree with the above poster. I bought a 2500k and it was easily overclocked from 3.3 GHz to 4.4 GHz. Now ALMOST anything will run at 100% even with LLE audio. SMG1-2 for example only go under 100% in some very rare instances. 4.5 GHz and 4.6 GHz were working fine too but I thought the voltage usage was a bit high for 24/7 use as I don't want to shorten my CPU's lifespan but if you want to live dangerously you can push this chip near 5 GHz.
Windows 7 64bit
Intel i5-2500k@4.5GHz
8 GB DDR3
Radeon HD 6950
Intel i5-2500k@4.5GHz
8 GB DDR3
Radeon HD 6950