Check Power options (in Control Panel), if set to High Performance, try using a Balanced profile. Sounds like something is keeping it from stepping down.
This does fix the problem, but the CPU is now "lazy" to boost to 4.9GHz, so when I game, I just manually set it to Performace Profile.
But, this is not ideal as in the past Performance Mode was the one stop shop.
Guess I'll have to do a fresh re-install of Windows 10 eventually.