My Power Options on my HP Envy 17 (i7) are set to keep a "Maximum processor state" of 100% when plugged in or on battery:

But when I unplug the laptop, The Turbo Boost Monitor and Processor ID Utility show the processor dropping from 1.85 GHz to 0.17 GHz.
Plugged in:

Unplugged, on battery only:

And of course it gets ridiculously sluggish. Am I missing something here? Why would my processor tank when it's still set to max out at 100% when unplugged?