If the overclock didn't help, it's most likely not your cpu but the dual gpu setup that is causing the frame drops.
Either way to your question: ghz is only a measurement of the "refresh rate". 1hz means the cpu starts a new cycle once per second, 1mhz 1.000 times per second and 1ghz 1.000.000 times per second. That however has nothing to do with how many instructions it can execute per cycle. Think of the cpu as secretaries whose job is to carry paper from a to b. Now, the amd guy runs from a to b and back 4 million times per second, the ibtel guy only 3.6 million times per second (well, those are two fast secretaries
. The amd guy only carries 20 pieces of paper at the same time, while the intel guy is stronger and carries 35 sheets at once. In the end, the amd one runs faster, burns more energy and gets hotter due to air resistance while the intel one gets more done.