Simple SATA/PWM question - everybody is telling me something different, what is correct?!

[Emiliano85]

Hi guys.

I'm new to building, and am just about to finish up my first rig. I'm using the Asus Crosshair VIII Hero, with the Ryzen 3950x.

My board has 9 headers meant for AIO/waterpump/fans in total - 5 of these are dedicated for fans: CPU_FAN, CHA_FAN1, CHA_FAN2, CHA_FAN3 and finally H_AMP. All are 1amp, minus the H_AMP which is 3amp.

I plan to use CHA_FAN3 with a SATA powered three-way 4-pin (both motherboard and fans end of cable) PWM splitter (not to be confused with a controller just to clarify my question), connecting 3 Noctua 0.15amp fans to it.

And yes i know individual fan control off one single header will not be possible, and that i have to be carefull not to overload one single header with too many fans (which is not the case here anyway = 0.45amp of fans into 1amp header).

So to my question, which nobody seems to be able to give me a straigh forward answer to is:

When SATA power is at play (specifically in a splitter - we are NOT TALKING about controllers) is it then overriding PWM control in every usecase?

Simple as that. One person tells me yes, SATA will always run fans at full speed, regardless of having a 4-pin connection between mobo. and fans in the same loop - while others tell me it's perfectly working - what else would the 4-pin cable going into the mobo. in that splitter be for?

So which one is it? There are so many much more complicated things out there in regards of building and hardware, you can quickly learn by Googling/asking people questions, but this one above, seems to be some kind of Bermuda Triangle when one try to get more knowledge.....

 

[JackCarver]

A SATA powered pwm splitter...the only pwm splitter I know looks like this:

Why do you need a SATA plug? Can you post a picture of your splitter?

Edit:
I searched for pwm-splitter at CaseKing, they were all like that one I posted above.

 

[londiste]

SATA (or Molex) may be necessary for running 3 or more fans from one header. Depending on fans, motherboard etc but that is usually when headers start running out of juice.
Given a proper splitter, PWM signal will come from motherboard via the 4-pin connector and SATA connection will only provide power.

 

[Emiliano85]

A SATA powered pwm splitter...the only pwm splitter I know looks like this:

View attachment 142481

Why do you need a SATA plug? Can you post a picture of your splitter?

So there is no definite answer to whether SATA+PWM works not in splitter cables?

I don't really need it, as the mobo. header provides enough power for the 3 fans as per my initial description. This type of splitter just happens to be the easiest one to get hold of (another thing that baffles me is how hard it is to find a normal 3-way PWM splitter without having to wait 5 years to order off Chinatown.net) where i am living unfortunately. I would prefer a non powered basic 3 way 4-pin PWM splitter, but at the same time i want to finish up my build now - it's just sitting and waiting for the last couple of bits. That's why i want to know, if this type will be okay for me - PWM is ofcourse a must, but since it's SATA powered, and people are telling me all sorts of stuff, i really don't know what to do from here....

This is the cable:

 

[JackCarver]

3 fans shouldn't be a problem to run directly at the MB. The pwm signal turns the power supply of the fan on and of and so you can control the fan speed.
If you plug the fans to a SATA controller I mean that they would run at full speed. The additional SATA connection I only know from Fan controllers.

 

[Emiliano85]

SATA (or Molex) may be necessary for running 3 or more fans from one header. Depending on fans, motherboard etc but that is usually when headers start running out of juice.
Given a proper splitter, PWM signal will come from motherboard via the 4-pin connector and SATA connection will only provide power.

So in other words, you are saying it IS POSSIBLE to have SATA power and still have PWM when in the same splitter/cable loop?

 

[newtekie1]

The answer is a little complex, because it is going to depend on the splitter.

Some splitters just have a dummy pin for the 4th pin, so PWM is disabled and the fans will run at full speed. I've only ever seen this on the super cheap splitters.

However, with other splitters, the PWM controller will work.

The splitter you just posted looks like it will work and the fans will be controller by PWM.

 

[JackCarver]

Don't use the SATA connection, only use the pwm connection to MB, that's my advice and it should be sufficient in your case

So in other words, you are saying it IS POSSIBLE to have SATA power and still have PWM when in the same splitter/cable loop?

No don't do so, only use PWM. You don't need that SATA plug.

 

[Emiliano85]

However, with other splitters, the PWM controller will work.

This i am aware of, problem is i can't get one easily. 2-way seems easy enough, but it's like 3-ways are illegal or somwthing, when you look at how hard they are to come about from a reputable webshop with quick delivery. Are nobody using these or how come?

 

[londiste]

This i am aware of, problem is i can't get one easily. 2-way seems easy enough, but it's like 3-ways are illegal or somwthing, when you look at how hard they are to come about from a reputable webshop with quick delivery. Are nobody using these or how come?

Power. An average fan header on motherboard can feed two or three fans. Splitter for 3 fans is likely enough not to work properly so they will not take that chance. Yes, enthusiast high-end motherboards can feed 3-4 fans without issue, sometimes more but it is not that relevant here as splitter can be used on any header and there is too large a chance to fail.

The splitter in your post will work. The 4-pin plug that goes to motherboard header will carry PWM signal and fan speed while molex will provide power.

 

[JackCarver]

A midrange MB can feed 3 fans as I used 3 fans on one pwm header on my Z370 MSI gaming carbon

 

[Emiliano85]

Don't use the SATA connection, only use the pwm connection to MB, that's my advice and it should be sufficient in your case



No don't do so, only use PWM. You don't need that SATA plug.

I appreciate your answer, and intention of trying to help - but this is exactly what i refer to in regards of mixed answers.

Using the splitter without the SATA connected was also my initial thought, but the question has become an obsession for me by now, as i can't believe it's so hard to find a definite answer. I want to learn as much as i can, as i really really started liking the game of building rigs, and might end up in a situation where i actually wanted to utilize all 5 ends on that splitter - in order to power 5 fans off one header (not that it would be a smart move) thus overloading it (if not for that SATA power). This time it's no problem, as 0.45 of total amps is fine on a 1amp header without additional power. But 5 fans would be another thing.

That's why i really want to know if this thing works, and if there is such thing as SATA+PWM working together or not.

 

[Deleted member 193706]

That's a molex connector isn't it, to power the fans if you don't have a spare fan header unless my eyes are mistaking me

 

[newtekie1]

This i am aware of, problem is i can't get one easily. 2-way seems easy enough, but it's like 3-ways are illegal or somwthing, when you look at how hard they are to come about from a reputable webshop with quick delivery. Are nobody using these or how come?

I think it is because the PWM circuit struggles with more fans. That is why PWM hubs exist.

Amazon.com: SilverStone Technology Silverstone 8-Port PWM Fan Hub/Splitter for 4-Pin & 3-Pin Fans in Black SST-CPF04-USA (Newest Version): Computers & Accessories

Amazon.com: SilverStone Technology Silverstone 8-Port PWM Fan Hub/Splitter for 4-Pin & 3-Pin Fans in Black SST-CPF04-USA (Newest Version): Computers & Accessories

smile.amazon.com

 

[JackCarver]

If you want to use 5 fans or even more, then really buy a fan controller, as it's the best solution.

In your case, you can use the SATA plug to power the fans, but then they run at full speed, independent if you use also the pwm plug. If you want to control your fans speed then only use the PWM plug

 

[londiste]

A midrange MB can feed 3 fans as I used 3 fans on one pwm header on my Z370 MSI gaming carbon

180€ motherboard is not midrange.

i can't believe it's so hard to find a definite answer.

The answer is simple for specific products. And you outlined the answer in your first post. Look at the motherboard specifications for the fan header - in your case most headers power up to 1A/12W (AMP and W_PUMP headers 3A/36W). With each fan consuming up to 0.13A you should be fine power 7 of these fans from one header (but I would still not recommend doing so). The same does not hold true for all fans - Noctua's fans are quite power efficient.

A simple example if a bit extreme fan choice to the other end - say you want to use a Noctua's industialPPC-3000 fan. That one has 0.55A in spec and it would be OK to run only one of these on one header.

External power source (usually a SATA or Molex connector) on the splitter immediately sidesteps this issue.

In your case, you can use the SATA plug to power the fans, but then they run at full speed, independent if you use also the pwm plug. If you want to control your fans speed then only use the PWM plug

If SATA plug powers the fans but both speed sensor and PWM control is connected to the motherboard, fan speed is still controlled by motherboard, achieving exactly what he needs. The splitter in post #4 does exactly that.

 

[Emiliano85]

If you want to use 5 fans or even more, then really buy a fan controller, as it's the best solution.

In your case, you can use the SATA plug to power the fans, but then they run at full speed, independent if you use also the pwm plug. If you want to control your fans speed then only use the PWM plug

Okay thanks.

But then my next question is: What is the purpose if such product (not that i expect you to know :-D)?

If it has SATA, it's meant to be used i guess - but it then renders the other part of the product (PWM) useless - then why put these two things together --> or more importantly why does this kind of product even exist.

 

[JackCarver]

It‘s an either or....either you use the SATA plug or the pwm. For example if you have no free pwm at the MB then use SATA

But not together

 

[TheLostSwede]

Ok, first of all, what you posted a picture of, has a Molex connector, not a SATA power connector. That part is to provide extra power to the fans.
The other end is for the PWM function and obviously connects to a fan header.
The question that springs to mind is this, are you connecting more than nine fans to your system (I only see eight PWM fan headers though)? Since as long as you're not connecting more than that many fans, why do you need a splitter? I used to run three fans off of a splitter, no extra power, so it works just fine.
However, there are slight variances between fans and having them all on a splitter, means you can't adjust them individually if there's one that creates a bit of fan whine.
If anything, I'd just connect a splitter without the extra power to the high amperage connector, as that would give you plenty power for the fans. I guess Asus is a bit silly with their pump connectors and don't allow them to be controlled.

It‘s an either or....either you use the SATA plug or the pwm. For example if you have no free pwm at the MB then use SATA

But not together

Did you not see the picture the OP posted? There are cables where you get power from Molex or SATA, but there's still a header that connectors to the board fan header for PWM of all the connected fans.

 

[londiste]

It‘s an either or....either you use the SATA plug or the pwm. For example if you have no free pwm at the MB then use SATA
But not together

No it isn't.
4-pin fan header pinout is: ground, 12V, RPM signal and PWM signal.
SATA (or Molex) is used in these splitters for ground and 12V while 4-pin that connects to motherboard runs RPM and PWM signals.

 

[Deleted member 193706]

No it isn't.
4-pin fan header pinout is: ground, 12V, RPM signal and PWM signal.
SATA (or Molex) is used in these splitters for ground and 12V while 4-pin that connects to motherboard runs RPM and PWM signals.

He didn't say they had the same function just that you use one or the other tbh it's been said 4-5 times in different ways by different people already and the op is still asking the same question

Edit :ignore the first part I misread your comment although are you sure there is no ground and 12v in the pwm connector on these splitters and there's a 12v molex option if you don't have a spare header, like some fans give you both options

 

[Emiliano85]

He didn't say they had the same function just that you use one or the other tbh it's been said 4-5 times in different ways by different people already and the op is still asking the same question

Edit :ignore the first part I misread your comment although are you sure there is no ground and 12v in the pwm connector on these splitters and there's a 12v molex option if you don't have a spare header, like some fans give you both options

Please forgive me for not having the Divine fan knowledge (and reading skills) as you my good Lord....

Ok, first of all, what you posted a picture of, has a Molex connector, not a SATA power connector. That part is to provide extra power to the fans.
The other end is for the PWM function and obviously connects to a fan header.
The question that springs to mind is this, are you connecting more than nine fans to your system (I only see eight PWM fan headers though)? Since as long as you're not connecting more than that many fans, why do you need a splitter? I used to run three fans off of a splitter, no extra power, so it works just fine.
However, there are slight variances between fans and having them all on a splitter, means you can't adjust them individually if there's one that creates a bit of fan whine.
If anything, I'd just connect a splitter without the extra power to the high amperage connector, as that would give you plenty power for the fans. I guess Asus is a bit silly with their pump connectors and don't allow them to be controlled.


Did you not see the picture the OP posted? There are cables where you get power from Molex or SATA, but there's still a header that connectors to the board fan header for PWM of all the connected fans.

Because the remaining headers are placed in a way that will result in unnecessary cable clutter. And I plan to run them at the same rpm anyway. So a splitter would be a win win for me.

 

[TheLostSwede]

Because the headers have been placed in a way that will result in unnecessary cable clutter. And I plan to run them at the same rpm anyway. So a splitter would be a win win for me.

You need to learn how to route cables

 

[Deleted member 193706]

Please forgive me for not having the Divine fan knowledge (and reading skills) as you my good Lord....


Because the remaining headers are placed in a way that will result in unnecessary cable clutter. And I plan to run them at the same rpm anyway. So a splitter would be a win win for me.

You come here asking how a fan splitter works then throw sarcasm at me? I'm out gfl with your thread

 

[TheMadDutchDude]

It's real simple. Not sure why everyone is complicating this so much!

SATA, or Molex, is there to provide the power only. Nothing more, nothing less. The 4th pin, for PWM, will still allow the fan to operate under normal PWM circumstances. You just need to make sure that you get one with PWM capability, most of which will say very clearly in the description of the item.

Jeez, oh man...