12v water pump with a 3 pin fan header... a little spooky

[glytch5]

I got a little phobya 12v water pumps... its a 3 pin fan cable for power... and it advertises the 3 pin cable for motherboard voltage control.

I have an MSI x370 pro carbon, and it even has a "pump fan" header.

Now this phobya pump is 8w!!!! at 12v... so thats nearly .7amps.... on a single fan header that seems like quiiiiite a lot of juice to pull through there.

Now on the other hand... when I was using my corsair h100i v2... that plugged right into my CPU fan header... and then 2 fans came daisy chained to that so... how many amps was that thing pulling? probably a lot! Or maybe not? idk!


Am I crazy for thinking that pullling .66amps through a single fan header is too much?

 

[InvalidError]

Most performance 120mm fans are in the neighborhood of 700mA, 8W shouldn't be a big deal.

 

[Scottray]

Generally, fan headers can supply 1.0A. Thus, a 0.66A draw is no issue.

 

[glytch5]

well... a while back I wanted to do multiple fans off a single header... I called MSI and they guy said plainly DO NOT EVER PUT MORE THAN ONE FAN ON A HEADER...
His reasoning was, the wires that deliver the power to the header are incredibly thin on the motherboard, and will melt down the solder joints very easily... I know when the pump starts it will probably spike up higher than .66amps at startup...

do either of you know how much power draw that corsair h100i was giving? that was on my CPU header, but it was no problem.

 

[n0ns3ns3]

This guy from MSI is not knowing what he is talking about.
Even though MSI makes crap, their MB can support more than 1 fan per header.
the pump headers are usually 2-3A which is way more than enough. for your pump even normal fan header with 1A is way more than enough.

 

[glytch5]

Hey there n0nsense. Long time no talk.
So have you actually done this before with a 3 pin pump? Thanks

 

[n0ns3ns3]

I've done it with D5 which is over 20w

 

[glytch5]

a 3 pin d5? I know a lot of d5s are 4 pin PWM... and they have the power coming from sata or molex, and the signal going to the mobo, as opposed to here where everything is coming from the mobo.

 

[n0ns3ns3]

well, changing connector is one of the easiest mods. i did it on Vario (non PWM) that had molex and 3 pin out of the box and remained with 3pin only supplying everything. that way I can control the pump speed via fan header.

 

[Scottray]

I'm skeptical of the MSI guy's answer. Mobo's are designed to handle the transients at power up. That's what the large capacitors on the 12V supply lines are for. There would need to be some huge, long lasting bounce and very high resistance on the fan header lines to get them hot enough to melt the solder joint.

I you want to be 100% safe, you'll need to buy a couple of fan hub controllers where the control lines go tho the mobo header and the power is connected to a molex connector to the power supply.

 

[glytch5]

The problem with fan hubs, is that only really works for PWM if you want to control with the mobo. for 3 pin, the only way to control the speed of the fan/pump is to change the voltage... which would have to come from the header... with PWM, you can change the speed of the unit with the PWM signal from the mobo. So unless it was a controller that did variable voltages controlled right on it, I do not think that will work.
For all my system fans I am using those splitter cables that take the RPM and PWM from the mobo, but power from sata. The 3 pin fans don't work for that though... just report voltage.

 

[n0ns3ns3]

all my fans are connected with splitters directly to the MB for both power and control.
I have no problem in changing voltage on 3pin headers for the non PWM pump/fans. Most motherboards (all Asus) can use DC or PWM mode on the 4 pin fan headers. D5 has 24v variant that runs ~6000RPM vs ~4000RPM on 12V.
Also, the vario model has the speed dial that actually reduces voltage to the motor.

 

[glytch5]

yes I know you can control the voltage with the mobo, but I was saying with the fan hubs, even if your mobo supports dc or pwm, you cannot control a 3 pin fan with the mobo, unless the voltage for that fan is coming from the mobo, which in one of these big super splitters case, you cannot control the 3 pin fans... since the power is not coming from it.

The way I understand it is, you have red and black, thats + and- then the yellow cable is the RPM readout... and then on a 4 pin fan you get that PWM control...

I would plug the pump straight into molex or sata conversion cables... but I want to turn down the speed, thats why the motherboard header appealed to me.

if you are saying that .66 amps ant ganna bother it, i'll take your word for it, but otherwise I do not see a way to control the speed of the thing... a low noise adapter can't handle that load either.
so with a 3 pin fan on a hub, unless that hub has its own voltage control, you are not going to be able to change the speed of a 3 pin fan.