So I have a z370 asrock extreme 4 and I'm trying to overclock my i7 8700k to 5GHz but can't even get it to 4.7 on a decent voltage and yet still crashes, I'm running a pre set 4.7 oc cuz Manual which works fine for my i7 6700k which is 4.7 and a Lower voltage doesnt work. So i7 8700k 4.7 1.36 v and my mates machine 4.7 1.30. Is there any other thing that needs to be changed in the bios because should be getting 5GHz and that current voltage of 1.36, if anyone knows fix would be good thanks