On 2021-08-22 4:30 a.m., Polyna-Maude Racicot-Summerside wrote: > > > On 2021-08-22 4:23 a.m., to...@tuxteam.de wrote: >> On Sun, Aug 22, 2021 at 09:56:19AM +0200, Emanuel Berg wrote: >> >> [...] >>> Fan connectors are 3-pin! >> >> Aha. So there's a chance. >> >> But still your drivers don't seem to play along. Hm. >> >> Ahem... it seems I was wrong: the third pin in three-pin conector seems >> to be tacho (i.e. speed feedback), not PWM [1]. The PWM is the fourth >> pin, which on a three-pin connector is the... oh, wait. >> >> Whether three-pin fans can be even be RPM controlled is an open question >> (the DC feed could be modulated, I guess, but I don't know whether it >> is actually done). >> > And there's the question of the system used to drive the fan. Could be > proprietary and not open. > > On budget motherboard, saving a chip is saving some cash and making profit. > > The significant difference in practice is that 4-pin fans allow for RPM > to change based on the need for cooling temperature, this reduces noise > and power consumption. While 3-pin can control the voltage, but the > voltage can't turn to change the fan RPM at all and accurate as much as > 4 pin fans. [2]
I'll add, changing voltage can't modulate the speed of a fan. You can only throttle it when you go into a close to stop. But this is really ineffective way of trying to control the speed. You'll be running at at most a hundred rpm. > > What Is the Difference Between Three- and Four-Pin CPU Fans? [3] > > > >> Cheers >> >> [1] https://en.wikipedia.org/wiki/Computer_fan#Connectors >> >> - t >> > > > [2] https://digitalworld839.com/3-pin-vs-4-pin-fan-difference-between/ > > [3] > https://www.howtogeek.com/273575/what-is-the-difference-between-three-and-four-pin-cpu-fans/ > -- Polyna-Maude R.-Summerside -Be smart, Be wise, Support opensource development
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