That does not sound like the correct temperature. AMD Overdrive is going to be the most accurate for your chip, or I find myself trusting MSI Afterburner or CoreTemp. Both are reliable and should give you around the correct temps.
12C is way too low for a CPU. Room temperature is about 21C. Your CPU cannot be lower than room temperature.
Moving on. 65C is considered the ideal temp for the chip, while 70C wouldn't be bad either, but it might shorten it's life span.
It's not a half bad overclock, but you could get more out of it if you didn't just up the multiplier and voltage, which is what I assume you did.
I have an FX 8320 running 1.49V and 4.7GHz. I get temps of around 52C to 60C with my water cooler while gaming, and 40 - 30C on idle.