That sounds pretty good to me. My cooler has similar performance to a 212 evo but it doesn't have a spot for a second fan, nor does it have much breathing room. My case is pretty cramped and my cooler is 'low' profile, meaning it's just not full height. With the same overclock (4.4, not sure about your voltage) I hit 90, but my CPU is pretty mediocre. With your temps I'd push it further unless you were shooting for a specific goal. My goal was 60 fps in my main FTB world and 4.3 had dips into the 50s fairly often, 4.4 was what I needed.
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its fine. as long as it doesnt get into the 90c range 70-80 is perfectly safe. actually 100c isnt going to kill your cpu, you just dont want to have it running at that speed for lengthy amounts of time otherwise things will start to melt.
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