What Voltage Do I Need for 4GHz on my i5-6600k?

[hereinmyferrari]

I have an i5-6600k and a hyper 212 evo with a Noctua NF-F12 PPC Industrial 2000 watt PWM fan attached to it. When browsing the internet and stuff like that, I get around 20 Celsiusat about 500-600 RPM and in games around 30 Celsius at about 900-1000 RPM. I want to overclock to 4GHz but I don't know what would be a good voltage for it.

So my question is, what is a good voltage to overclock to 4GHz and have it be stable on my i5-6600k with a hyper 212 evo?

 

[BadActor]

Turboboost will give you 3.9 at stock voltage. I would think overclocking to 4.0 at the stock voltage (1.2) is possible with most CPU's. I have mine at 4.4 with a 1.27 vcore.