Need overclocking help

So today I tried overclocking my i7-6700K to 4.5GHz and I've had a lot of issues with doing so. I've tried 1.3v, 1.325v, and 1.33v and they all failed. 1.325v probably lasted the longest but I don't know what I'm doing wrong, I don't want to go any higher since I'm scared to do so as I don't want to fry anything. Any help will be appreciated and I'll be looking myself as well as asking here. Thank you to anyone that helps .

Edit: Am I just using too high of voltage and my CPU just crashes?

 

A little bit of research says you can get higher voltage without issue, but let's hold off on that for the moment. Have you tried overclocking on any lower speeds? If you could, what was the highest you've tried and what was your voltage?

 

What cooler? Not sure if speeds can reach that high on stock fans.

 

Delid it and apply better cooling paste.

 

When does the crash happen? During stress test or in the boot?