Originally Posted by
Buffalobiian
If I tell you this i5 is rated for 2.8GHz, it means that each of its four cores run at 2.8GHz. If you would like a "total", then that would be 2.8*4 = 11.2GHz.
Processors these days have underclocking and (the term used by Intel's processors is) Turboboosting. The i5 760 is rated at 2.8GHz, but will underclock to 1.2GHz to save power and heat when not demanded, and can Turboboost (dynamic overclocking pretty much) up to 3.3GHz given that it has the thermal headroom and other resources available.
In other words, the i5 760 (2.8GHz) is garunteed to run between 1.2-2.8GHz. If it's not overheating, it can turboboost up to 3.33GHz (though this performance is subjective to operating conditions - heat and threads).
The newest gen of i3s/i5s have even more amazing turboboost capabilities. AMD has something similar too.