Sounds like maybe the Windows KB4100347 Intel CPU microcode update that kills overclocking on some CPUs got installed..Open Windows Update, then View Update History, then Uninstall Updates and see if it's in the list of updates you can right-click to uninstall..Another update may have got installed that kills overclocking too.
 
 
There's ways to hide and block most updates without totally disabling Windows Update, more on that later..But you can turn on Metered Connection for now in your network properties to stop most updates from auto-downloading and installing..You can also Pause Updates within Windows Update.

Cool 

I set my internet connection to 'Metered' and then run wushowhide tool to check for Windows Updates first before running the normal Windows Update..Then I can hide (or show again) an update from the normal Windows Update before running it..Then I run the normal Windows Update to download/install other updates..I have wushowhide set to run on a schedule (8am every day) by creating a basic task (with highest privileges) in Task Scheduler..That gives me a chance to research updates to see what they're all about and if other ppl have issues before installing them..I also choose not to check for updates during the Windows install, I do that myself later just exactly for that reason..I hate that Win10 will install every non-optional update that comes down the pipeline as opposed to older Windows versions where you could pick and choose.

You can hide that KB4100347 update forever and ever using the wushowhide tool from Micro$haft.

How to Hide or Show Windows Updates in Windows 10

How to Create Task to Run at Logon in Windows 10

notfordman
Bob, you are just full of great info. Thanks for all your help. {and you do often} 

Thanks man..Been around a while, hopefully way more longer 

I am wondering, isn't that update a patch for Spectre vulnerability ?