How can I disable overclocking on my motherboard?

[richard.lajko]

First,sorry for my english.I've been trying to disable overclocking function on my motherboard for a long time,but i just can't figure it out how to.I did not overclock my cpu by myself,my motherboard auto overclocked it.(From 4.2Ghz to 4.5ghz)
My motherboard: Gigabyte GA-Z270X-Gaming 5
CPU: Intel i7 7700k
The reason why i want to set it back to default 4.2ghz,beacuse i've water cooling(Enermax Liqmax II 240) and my cpu under stress(while i am gaming) is near 90 celsius.The avarage temperature of the cpu is ~75.I don't know why,maybe i've bad cooling?
I tried to disable overclock in bios,but i didn't see anything there that could help.

 

[Dunlop0078]

4.5ghz is the stock turbo clock speed for the 7700k, it's not overclocked. 75c at idle? That cooler should do WAY better than that I would make sure the pump is working properly and you have it installed correctly.

You can underclock it to 4.2ghz if you want by changing the multiplier to 42. Or by turning off intel turbo clock. This may not affect temps however, if you want to decrease temps significantly you will need to underclock and undervolt the cpu. Regardless you should fix whatever is wrong with your cooler first.