Question about Intel Core i7-6700K Box

As long as the voltage is not higher than 1.4v you will have no problems.

Intel does not support overclocking you will lose the warranty.
However, you can't check this, just don't state it.
And never send in decapitated CPUs!

This processor has a k in its name, which means it has a free multiplier. This processor is designed for overclocking. The warranty does not expire in the process.

From the Haswell 2013 generation onwards, such as the 4770k, you can overclock without losing your warranty. This was introduced and confirmed by Intel