There's no danger in doing so - and I've actually considered it so that I could make a "quiet" PC with no CPU fan. It's perfectly acceptable and won't break anything.
Problem is, that's a SERIOUS pain in the ass. Used to have the "Turbo" button on cases that would automatically throttle the CPU down whenever you needed to do something like that. There are lots of old games that have that problem. Talk about poor programming
Anyway, I personally am not aware of any Windows utility, though I'm sure one exists. If you want, I can write a program that will eat up loads of CPU for you
The alternative is to upgrade the game to Quake III Arena.