On Sun, Aug 22, 2021 at 04:02:48PM +0200, Emanuel Berg wrote: > tomas wrote: > > > I disagree. The thing poses [1] as a DC motor (2 pins power, > > one tacho). I don't think you get too much control over RPM > > That's what you get with the 4th wire/pin? A sensor to > read RPM? Re-read the Wikipedia I quoted: according to that, that's the third pin of the three-pin thingie (aka tacho, like bikes have :) The *fourth* pin is PWM, i.e. speed control. Debate's up whether you can control a three-pin fan by regulating its DC voltage (the motherboard/chipset would have to provide that, of course). Some of us say it can be done, rhkramer says it has (at least) been done. > "What you can't measure, you can't control" ...it rather controls you ;-) I think the tacho originally was important to have a "live signal", in the times fans were more unreliable. If it gets stuck because the bushing went bad, software can take action before the CPU goes in flames. These days things fail more gracefully at several levels. Cheers - t
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