Speedfan is not just to read values. You can make your machine act on them.
I have a water-cooled machine. Not for overclocking, but because I want a silent machine. The problem is, when you don't hear any fans, you'll start hearing other things. And the worst thing was: the water-pump can be quite loud. Now that the water-pump made my machine silent, the water-pump itself became the biggest problem !
I tried a bunch of things, but the pump was still audible. So I ran my pump at lower speed. The default speed is 3500 rpm. But it runs fine at 2200 rpm too. And the noise drops tremendously. How to make my pump run slower ?
So I used a fan-controller. To make my pump run at 2200 rpm. That is done by lowering the voltage by hardware in the fan-controller. The problem is: when I reboot the lower voltage is not enough for the pump to start. So I bought a more expensive fan-controller, which lower the voltage only after a few seconds. That kinda worked, but not reliably. Sometimes my pump wouldn't start. Not good.
Then I plugged the power-cable of the water-pump into the motherboard where the power-cable of the cpu fan goes. And then I used speedfan to control the speed of the pump. Worked great. And a lot cheaper than a hardware fan-controller. And the beauty of this solution ? I used Windows Task Scheduler (Taskschd.msc) to start speedfan after reboot. But I configured the Task Scheduler to start Speedfan 1 minute after boot. So my pump always starts. Works flawlessly for years now.
If I ever have to re-install Windows, Speedfan will be the first application I install.