A little over a year ago i bought a 3770 non k because i didn't believe i had a need to overclock. I just recently picked up a 780 SC and notice that i fall behind on a lot of benchmarks i see online of people using the k version. Is my CPU holding back my GPU?
No it is not holding back your graphics card, its just that the 3770k has unlocked multiplier which as you said can be used for overclocking. which means that the users that use 3770k has already overclocked their cpu. It would be faster than just the 3770. But it wont hold your gpu back.