1.2V is a very good voltage for 4.5ghz, as well as temperature, on Haswell. You have received a good chip, you can always try lowering voltage -0.05 until it is no longer stable, then go to last stable voltage. Overall, it looks great so far.
seeing your temps are around 80 degrees already is that max load or just gaming, because overclocking more and changing the voltage higher will most likely increase it by quite a bit, what cpu cooler do you have?
I think we may have gotten ours from a similar batch cuz i can run 4.5 @ 1.2v no issues at all, but I'm using and H80i so my at load temps are like 54c, could pull of 4.6-4.7 maybe but the voltage jump to get there is too 1.28v though