Do you remember this?
Your turbo multis are working fine now with this set at 22 so the Non Turbo Ratio is not causing the problem.
Thanks for running RegReport. Not sure if I will ever figure out what has changed but at least I have lots of numbers to look at. The version of TS I sent you today is good until the end of the year. Send an email to the guy in the About box of ThrottleStop and I will send you an updated version of TS 8.30. Hopefully I get something figured out before then.
Adjusting BCLK is beyond me and it is beyond ThrottleStop. Even if adjusting the BCLK was possible, it is usually only good for a percent or two before you lose stability. Definitely not worth it.
Enabling C3 allows the 27 multiplier to be used when a single core is active. If you want to confirm if this is for real, try running a SuperPi Mod benchmark with and without C3 enabled.
https://www.techpowerup.com/download/super-pi/
This is a single threaded benchmark so it should confirm that C3 enabled allows the high multi and gives you the best performance.
Some Haswell CPUs had a bug so using an early microcode allowed you to run the highest turbo multi full time no matter how many cores were active. Not sure if this would be possible with your CPUs. Probably not.