PWM Sense Wire Question.

[TheDeeGee]

I have this 3-Way Daisy Chain PWM splitter, but all 3 fans have the Sense Wire connected, causing the fan readout to sometimes read 0 RPM because it get's confused as all 3 fans send pulses.

Will this hurt the motherboard fan controller in the long run?

Otherwise i'll push out the sense pin at the fan itself, as that appears to be the easiest way with a needle. I don't wanna resort to cutting the sense wires from the splitter.

 

[Deleted member 185158]

Maybe push the pin from just 2 of the fans and use one to pwm controll all three in the chain.

 

[Shrek]

A splitter should only carry one sense wire.

 

[TheDeeGee]

Ended up cutting the other sense wires in the chain and removing the pin, now only the first fan get's pulsed.

A splitter should only carry one sense wire.

Seems Moddiy changed them since last time i bought them.

Premium Sleeved 4 Pin to 3 x 4 Pin PWM Daisy Chain Fan Splitter Cable - modDIY.com

As the ones i gotten had all the wires connected for all fans.

 

[Shrek]

Scary that they sold such non-sense

 

[doyll]

As stated it's best to use single fan rpm signal. Then rpm reading is accurate for that fan.
That said, I've seen many splitters / hubs that connected more than one rpm signal and have never had it cause a problem except in visual rpm reading. My guess is little to no fan control software actually uses rpm signal to control fan speed. Software simple increases/decreases fan voltage or changes in length and/or frequency of 12v pulse as temp goes up / down. As temp goes down fan voltage / PWM pulses are shortened. As temp goes up fan voltage /PWM pulses are lengthened. Software has RPM for user interface only. It's my guess based on running fan curves with no rpm signal from any of the fans in system many years ago. Maybe some new fan control software now does use RPM, but it would only complicate things. KISS principle applies here.

 

[cvaldes]

As stated it's best to use single fan rpm signal. Then rpm reading is accurate for that fan.
That said, I've seen many splitters / hubs that connected more than one rpm signal and have never had it cause a problem except in visual rpm reading. My guess is little to no fan control software actually uses rpm signal to control fan speed. Software simple increases/decreases fan voltage or changes in length and/or frequency of 12v pulse as temp goes up / down. As temp goes down fan voltage / PWM pulses are shortened. As temp goes up fan voltage /PWM pulses are lengthened. Software has RPM for user interface only. It's my guess based on running fan curves with no rpm signal from any of the fans in system many years ago. Maybe some new fan control software now does use RPM, but it would only complicate things. KISS principle applies here.

The rpm signal (on pin 3) is called SENSE for a reason. It handles speed data provided from the fan (or other device like an AIO pump). The PWM signal (on pin 4) is also called CONTROL because the controller (hub or motherboard) is sending fan speed commands on that line. Neither pin hosts a bi-directional data signal.

The rpm signal is also helpful in creating fan curves for different speeds at different temperatures.

 

[doyll]

The rpm signal (on pin 3) is called SENSE for a reason. It handles speed data provided from the fan (or other device like an AIO pump). The PWM signal (on pin 4) is also called CONTROL because the controller (hub or motherboard) is sending fan speed commands on that line. Neither pin hosts a bi-directional data signal.

The rpm signal is also helpful in creating fan curves for different speeds at different temperatures.

It's called SENSE because it's a sensor sending current pulses that are converted to what we see as rpm.
Indeed, PWM signal controls revolutions. same as changing voltage. We could use percent of total speed instead of rpm. In fact some controllers (like MSI Command Center) fan curves use percent of fan speed and temp instead of RPM and temp.
Of course neither is bi-directional data signal.
So what are you saying?