Whether they are controlled by your motherboard or by a dedicated controller, your PC's case fans cycle up and down based on how hot the control software thinks your computer is. The problem: most computers get temperature and usage readouts for the CPU and GPU, but not for the exact area where your case fans live. You might have case fans that are very far away from your hottest components and perhaps they could be spinning less (or more) based on the temperature on the top of your case or the front or the bottom.
Thermaltake's new TS120 and TS140 case fans are the company's first to have built-in temperature sensors which allow each one to know exactly how hot or cold it is in that section of your case. Then the upcoming TT Plus RGB 3.0 software will allow you to view the temperatures and control the fan curves, presumably (though this hasn't been confirmed) on a fan-by-fan basis.
