Hello, thank for taking the time to write this all up @mgutt
It'd be appreciated if someone could look at my BIOS settings and see where I'm going wrong with enabling C-States. Since taking the photo I have disabled turbo mode. I also tried changing the 'Package C State Limit' from Auto to C7 with no luck.
Running a Asus Z170-WS with an i7-6700
I've also enabled something called 'EPU Power Saving Mode' in the BIOS which is described as "The ASUS EU (energy processing unit) applies settings for minimum system power consumption, Enabling this will apply lower EPU Core/Cache voltage and heip save energy consumption, Leave disabled if overclocking the system"
The manual for my motherboard has the options listed as such;