Well, Microsoft hid this one and most likely comes across when the machine performs a reboot to do the setup of the new build received. It does not show up on any list. Now, this is pertaining to "builds" for the Windows Insider program. On normal RTM
releases, Firmware updates do appear in the Windows Update panel.
You will get the Firmware update!
The Insider builds are an experiment for the next RTM release. They test internally to make sure it doesn't destroy anything and then send it out to the Insiders to get feedback.
This particular firmware update is working so far.
Now, that hack you have been doing with the CPU - change it back to normal! I don't care about what articles you have been reading about hyperthreading, most of those are bogus. Intel has a lot of issues regarding their CPUs even when operating normal.
Also, recommend to stay away from the BIOS as much as possible. You can accidently crash it and turn the machine into a brick in less than one second (my first Surface Laptop did that).
You will get the Firmware Update that the Insiders are getting. Microsoft's next even is October the 2nd which is the date I keep seeing and Microsoft generally releases the next upgrade around noon on the same day.
Be patient!