I recently purchased a new ASUS TUF X299 motherboard and an Intel i9 processor with 16 cores (32 CPUs / threads). The processor runs at a default of 2.8 GHz but is actually capable of being overclocked to much higher speeds on this Fedora 27 box.
I really don’t care about getting the last bit of performance out of my computer; I really would rather have reliability than maximum speed. But I do want a bit more than 2.8GHz.
After fussing with the system for a few days and not getting any stable results, I decided that it would be interesting to try reinstalling fedora from scratch. For the last several versions I have been doing upgrades rather than reinstalls, so I thought I might as well try the reinstall. That did work for me and I was able to get to my target of 50% overclocking without any trouble.
You should note that the Fedora Project recommends not overclocking your CPU. https://fedoraproject.org/wiki/HardwareProblems
The bottom line in this case is that Fedora should be installed from scratch on a host in order to ensure best performance from these newer and very powerful CPUs.