go to your bios; CPU configuration options (or something similar); and it will be an option there.
I don't see why this would be an issue, it might make it a little cooler turning it off, but it would also decrease performance, you might want to google "overclocking guide" and play around with your CPU voltages, all the time you are spending here and worrying about this could be spent finding the optimal voltage and I would say you have a good chance (with a bit of work) of getting a more significant improvement in temperatures
it will take time to test the overclock but as far as actual learning and effort, not much of these can give you a significant improvement
just what i would do... have fun