A 6700K at 4.5ghz is like a 2500K at 5.5-6ghz at least... you have to look at how the CPU is pulling or if the OC you have applied is not stable and is giving you performance problems.
That's what I meant, that your numbers match what it apparently has to yield, perhaps I was misunderstood with the 6700k at 4.5Ghz.