Oh, fun fun fun! 2500k overclocking!!
))
Well every CPU is different, because of what we call the "silicon lottery." This means that the silicon wafers the chips are printed on are not exactly the same, which means that the voltage I need for 4ghz is gonna different than what you need.
That being said, I have run 4.5ghz on 1.3volts, and now Im running 4ghz on 1.21 volts, so I'm pretty sure you dont need 1.33 for 4ghz. And because of that high voltage, you are getting high temps. (70 isn't dangerous or anything, its just not a great temp. But of course, with stock clocks and volts on the stock cooler it runs at 80, so...)
What you need to do is:
1. Decide on what speed you want and set it via the multiplier.
2. Turn on all the OC stability stuff you mobo offers. (PLL overvoltage, Load Line Calibration, Phase Modes, etc.)
3. Test for stability, lower your vcore, test, lower, etc. (Until its not stable and it crashes.)
4. Once it crashes go write down what voltage that was, and bump your vcore up to a little bit over that.
My 2500k is running 1.21volts at 4ghz, start at 1.25, test, and work your way down. Good luck!