I don't know the ins and outs of Mach3 code, but I do know it isn't "just another app" sat on top of the OS, instead it uses in effect fake realtime code, which is going to bypass any BIOS aware OS code that is for example stepping the CPU clock.
But, all these "green" features are simple to disable in BIOS anyway in every desktop I've ever seen.
I just can't get my head around why people would (given the effective free cost of an old desktop or server box) insist on using a laptop though, which would have a far greater level of such tricks to be disabled, even assuming all of them could....
for example good luck downloading and flashing the "OEM" BIOS onto a dell laptop (instead of the dell BIOS)
Mind you, I have had this (I/O flexibility) conversations with vaxen / PDP-11 owners, who just couldn't understand how our megahertz cpus with astonishing 4 megs of RAM couldn't hold a candle to what their PDPs could do in a few k....