It sounds like whoever did the overclock didn't make much of an effort. They just set the voltage to 1.275V because they knew the overclock would probably be stable. They may have even just changed the CPU multiplier and left the voltage on auto, which is lazy to say the least. What they should have done is test the overclock and lowered the voltage in-between tests. That way, you get a stable overclock whilst keeping the temperature as low as possible.
If you're running the Prime95 Small FFTs test and get temperatures of 70C after ten minutes, then you can just leave the overclock alone and be done with it. Personally, I'd advise that you learn the ropes so you can tweak the overclock and diagnose any problems that may arise.
CPU overclocking should always be done in the BIOS.