Well, you could try reapplying your thermal paste. However your temps are already pretty good for 4.5 ghz and 1.3volts.
I've got the same setup actually, 3570k with a z77 extreme6 and a 212 evo in push only (carbide 400r case tho). I haven't successfully gotten 4.5ghz yet, but I've gotten 4.4ghz stable without any extra voltage and I was at max 65C after 9 hours of Prime95 (I know, I ran it too long, but nothing went wrong). The AsRock extreme6 auto turbo mode (the top option in the UEFI/BIOS) doesn't work right for me. It just makes my cpu overclock to 4.7ghz without the proper voltage and I get a BSOD within 5 seconds. Dunno if you've tried/experienced this yet.
So getting 80C max after 2 hours of prime95 with too much thermal paste and extra voltage is definitely "normal". I'd try lowering the voltage though as much as you can. You could also try using a voltage offset instead of just making the voltage 1.3v by default. If it matters enough to you, you try using some arctic silver 5 thermal paste (which is what I used) and apply just barely enough to cover your cpu. You might notice a drop in your avg temps by 2-5C (less is more when thinking about thermal paste).