The controller you referenced gets the temperature from sensor pads that go to the controller.
Read the product reviews from the web site and you will get a good idea of how it works.http://www.nzxt.com/new/products/fan_control/sentry_2
But... What do you want to accomplish?
If you have fans that are attached to motherboard headers, they can be controlled with a free app like speedfan, or by motherboard bios settings.
Even then, I prefer to set my fans at a constant speed. I find that it is much less annoying to hear a constant drone rather than a constantly changing noise.
If the parts occasionally get a bit hot, so be it; they are built to take heat, and protect themselves if things get really hot.