Thanks, I tried 1.25 volts and got BSODs; should I try lowering by smaller amounts?
After researching thermal paste application (which I foolishly didn't beforehand) I realized I applied too much. I used the CoolerMaster supplied tube and spread the whole thing on. Is this likely to make a big difference? Is it worth redoing with some new paste?
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).