Hi all,
I've watercooled my 3090 FTW3 Ultra. I've done a separate Loop only for my VGA so there is a Pump (EKWB Kinetic) that works only for the 3090.
There's a little problem:
EKWB Kinetic has 2 cables: 4 Pin Molex (to PSU) and a 4 Pin PWM (to PWM out). The 4 Pin PWM that comes out from the Pump, only has the last 2 cable (tach and pwm) because Pump takes power directly from the PSU.
I've connected the PWM to the external FAN Header of the 3090 but the Pump is always running at 100%. I've tried different configurations in Precision X1, but even when I set 20 or 0% I can clearly see 4700RPM (full speed).
It seems like that 4 Pin PWM out not works in PWM mode but in DC mode.
Can anyone help me?
Thanks you in advance

Cool GTX
Can you control RPM from your MB pump header ? - that is the normal connection
 
yep, Will run at 100% duty cycle - when PWM feedback signal is Not present
 
 
 What is PWM and how does it work?

How is possible that I can control my second pump (CPU one) with every cable linked in the same way and the PWM one is connected to a normal fan header on motherboard?

rjbarker
If your pump comes with both a Molex Connector and a PWM cable try unplugging the Molex to PSU and just plugging in PWM to Mobo....the PWM Cable should be able to power pump and controllable thru software BIOS (I think). Just be sure that particular Fan Header is set up properly in your BIOS, as in enabled (otherwise it wont work if disabled).
Think of that PWM cable as a fan cable, same thing...provide power, monitor and control fans.
My D5 Vario pump is set up like yours w a Molex to provide power to pump, but I have a 2 pin connector to Mobo just to monitor speed....the speed is controlled manually thru a a simple dial on the underside of the pump.

Can't disconnect the molex, Pumps needs like 40W to work properly.
The way I connect everything is correct (the Pump on my CPU works very well and I can edit the speed curve).
Can't understand why the same kind of connection doesn't work on the VGA....

What do you mean "pumps" plural...are you not running a single open loop with one pump for both GPU n CPU?
I have never heard of a "Kinetic Pump"....
 

antsh415
The PWM cable on the Kinetic pump only has 2 wires: the tach wire and the PWM signal wire. You can't power them with the PWM cable. The Molex cable is the only one you can use to draw power. Also, yes an absence of signal on the pwm signal wire will cause the pump to operate at full speed.

 
If the Header Cable only has 2 wires and not 4 then its not a true PWM header....2 wires = 1 Ground and one to monitor RPM of pump (like my D5 Vario).....I would think....although not familiar with this pump....but mine as well comes with Molex to power pump...the 2 wire header is only to monitor RPM (like all 2 wire headers monitor only).....not sure how your supposed to control RPM of pump if no manual control and no actual 4 wire PWM plug.

Can you take a screenshot of PX1 after setting Fan 4 to 50% and hitting apply?

^^^^ I see......why run 2 separate loops w 2 pumps etc...this is generally for multi GPU's and even them I have never required 2 separate loops (ran a SLi set up w full cover blocks prior to the 3080), not that I'm being negative its just that it adds more complexity when its not needed for a simple GPU / CPU cooling loop

RKR21566

Cool GTX
Can you control RPM from your MB pump header ? - that is the normal connection
 
yep, Will run at 100% duty cycle - when PWM feedback signal is Not present
 
 
 What is PWM and how does it work?

How is possible that I can control my second pump (CPU one) with every cable linked in the same way and the PWM one is connected to a normal fan header on motherboard?

Good question.  It should be very possible.  You are doing nothing wrong.  It is such a simple standard.  Time to contact EVGA and ask them what gives.

Tested this on a 3080 FTW3 Hybrid obtained in the second batch in December. Yeah the external fan plug does variable voltage, not PWM like it (maybe?) should.  Checked with a multimeter, tried a powered hub and just a pwm fan.  I wonder if it's a firmware issue or if they somehow just put a voltage adjustment chip on during the design phase and nobody caught it.  Bizarre. Does read tach and there is 5V on the PWM lead.  Looks like I'm back to flashing an Ultra bios, or hunting down a voltage to PWM signal adapter.
 
Interestingly though, with the right adapter cable you could plug your hybrid pump into it and control the pump, on board with a custom curve.