I have just flashed to the latest BIOS version 3208 which has finally fixed my issue.
Previously if you had SpeedStep and Turbo enabled and set a multiplier of 40, it would ignore speedstep and lock it to 40, now I get the whole range; from 19 to 40.

There is an issue flashing to this BIOS version; in that you have to do it twice. I had an issue using my mouse inbetween flashes, but once I started using the keyboard to navigate it was fine.