Question Settings for OC i5 6600K Asus Z170

[krn4]

Hi, I am OC my i5 6600K on my Asus z170 motherboard. I followed the guides online, but they are all for 4.5+ GHz. on 4.5 GHz the OC failed, so I tried 4.3 GHz. When stress testing on 4.3 GHz my core temp sometimes went above 90C, what settings should I change? I am not sure what the voltage should be if I try e.g. 4.1 GHz

 

[Cdog042501]

Whats your cooling solution?