Skylake non-k overclocking on MSI z170A TOMAHAWK AC ?

[Safire]

Hello, I want to buy MSI 170A TOMAHAWK AC to overclock my i5-6400. I want to ask you is it still possible to do that on old bios ? Ive heard that someone had problem with overclcoking non-K intel cpu, even on older bios, is there anyone who is running or tried non-k oc on that board ?

 

And i would like to ask you, is there a bios difference between MSI Z170A Tomahawk AC and Tomahawk ? They are completly the same boards, just AC have added wifi.

 

Thanks !