IIRC the extra pin on a 4 pin motherboard header may report if the fan has totally stopped, like a failure line, to tell the mobo to shut the CPU off. I've got an old 4 pin fan here from a '94 vintage ...

The point of this guide is to show the latest and greatest in fan control technology on Intel Z270 motherboards and to help you understand what each brand has to offer in their high-end products. I ...

If your computer's running a little loud for your tastes, it's probably because your fans are running at full speed—even if they don't need to be. Here are a few ways to manage your fan's speed so ...

On page 4, there is an "IDE Power" connector. It looks a lot like a 4 pin CPU fan connector, but it (obviously) provides different voltages that are appropriate for 3.5" IDE drives (5V, 12V) and the ...

The CPU OPT header is an additional connection for special processor cooling accessories, such as specialized coolers with multiple fans or water-cooling components. Functionally, CPU OPT is identical ...