The CPU clock is dynamic so it will jump around depending on the P state and the CPU load
when loaded it will move up to full speed and when saturated it will activate the boost clocks
loading up a game does not do this. its still clocked around 1.5Ghz. Insurgency for example, i get over 200 frames when OC. earlier when i tried to play it i barley got 60. this could however be a setting in the bios i need to fix?
Try disabling C-state in the bios and see if that works and also Windows Fall Creator's update seems to fix a lot of these issues, I suggest you update if you haven't already and also turning off Cool&Quiet seems to help and try setting your power plan to high performance.
I suggest checking for a BIOS update weekly to see if the developers have figured it all out yet