Mixed push/pull fans on 360 AIO

[Kleetz]

Just built a new Ryzen 5 2600 (non x) gaming rig and joined overclockers, first post whooo!

I searched and there is a post about this topic, but I didn't want to resurrect a post that's over 1521 days old.

As mentioned above I have a R5 2600 (non x), ASUS Prime Pro x470, 16gb 3200MHz ram, and a Fractal S36 AIO with Corsairs HD120's. Using Ryzen Master, I can get the 2600 to 4.075 @1.375V. Anything more even with more voltage and the screen freezes and I need to restart. Maybe it's something deeper and not a thermal issue.

Regardless, my question is: can I do a push pull with the Corsairs HD120's and the Fractal fans that came with the AIO?

Here are the specs for both fans:

Corsairs HD120s:
800-1725 RPM
2.25 mmH2O
54.4 CFM
Max input current: .3A
Operating voltage: 7 - 13.2V
Hydraulic bearing

Dynamic X2 GP-12
500-2000 RPM
2.30 mmH2O
87.6 CFM
max input current: .2A
Operating voltage: 7 - 12V
LLS bearing

I'd want the Corsairs to be the push fans (because RGB) and the fractals to pull.

Thanks for any input / advice!

 

[GenkiM]

Regardless, my question is: can I do a push pull with the Corsairs HD120's and the Fractal fans that came with the AIO?

Here are the specs for both fans:

Corsairs HD120s:
800-1725 RPM
2.25 mmH2O
54.4 CFM
Max input current: .3A
Operating voltage: 7 - 13.2V
Hydraulic bearing

Dynamic X2 GP-12
500-2000 RPM
2.30 mmH2O
87.6 CFM
max input current: .2A
Operating voltage: 7 - 12V
LLS bearing

I'd want the Corsairs to be the push fans (because RGB) and the fractals to pull.

Thanks for any input / advice!

Congrats on the new build

As for the question: that shouldn't be a problem in terms of air-flow. Although the Fractals move more air your Corsair's are you primary fans, not because of performance but because of the RGB, and they won't be restricted by the Fractals because the Fractals spin faster and move more air than the Corsairs. If it were the other way around I'd suggest more powerful fans for pull to stop the Corsair's being restricted, but as it is, in terms of airflow, it should be fine.

Two things to look out for however:

Firstly, look out for noise when blending fans. Sometimes when two fans operate in close vicinity to each other the motor noise can blend and create harsh and/or intrusive tones, so that might be worth testing before you install and mount everything, and testing with them mounted on the radiator is a good idea, because where a fan's mounted and on what surfaces etc. can cause changes in motor noise and resonances through the surrounding enclosure.

Secondly, and much more importanly, if you're running two of each of those on a 240mm rad the combined current of those four fans will be 1 amp. While I believe a lot of motherboard headers are rated at 1 amp (and that's something that needs to be checked from motherboard to motherboard) when fans start up they draw more current to get the blades moving (it takes less to keep them moving but on startup they need to draw more to jolt the fans into action), so with that many fans plugged into one fan header you'll in all likelihood get spikes that exceed 1 amp, which can potentially damage the fan header (depending on the maximum current it can support).

The specs you've included have the current listed as "max input", but I couldn't tell you if that takes the voltage spikes into account, or if that's a measure of what they draw at their full speed. That would be good to know; I don't have that answer. Nor do I know the percentage by which, on average, it's operating current will be exceeded at startup by any given fan. Also would be good to know.

But anyway, if both types of fan were PWM fans I'd suggest something like this, which shares the PWM signal but lets the fans draw power from a source external to the Motherboard: http://www.akasa.co.uk/update.php?t...ype_sub=Fan Cable Adapters&model=AK-CBFA07-45

However, the Fractals it seems are three-pin fans so, if you plug those in to an adaptor such as that which I've linked to above, they'll just run at full speed.

I'd suggest running the two different types of fans either from two different headers (it's generally accepted practice to run two P.C. case fans from one header, and motherboard manufacturers do take this into account, although it is always best to check these things just to make sure, especially with low end motherboards and especially if they come from lesser known manufacturers) or, if you don't have enough fan headers to do that, then it might mean looking into purchasing a fan controller, either digital or analogue (depending on your needs and preferences).

 

[Kleetz]

Thanks for the detailed reply!

Sound: I'll look into how they sound together, but I don't think that'll be an issue.

Power: The ASUS Prime Pro has a CPU fan header and a CPU OPT header right below the main one. I was going to power the Corsairs off the main CPU header and the Fractals off the OPT header. I think you mentioned powering them off two separate headers further in your post, so we're in agreement here, right?

Control: The Fractals are 4pin fans, so I'll be able to control them via PWM. That being said, should I adjust the fan curve of the Fractals to match the max speed of the Corsairs (basically set it so they can't run at 100%)? Or is the difference small enough that I can have the same fan curve for each set?

Kleetz

 

[GenkiM]

Thanks for the detailed reply!

Sound: I'll look into how they sound together, but I don't think that'll be an issue.

Power: The ASUS Prime Pro has a CPU fan header and a CPU OPT header right below the main one. I was going to power the Corsairs off the main CPU header and the Fractals off the OPT header. I think you mentioned powering them off two separate headers further in your post, so we're in agreement here, right?

Control: The Fractals are 4pin fans, so I'll be able to control them via PWM. That being said, should I adjust the fan curve of the Fractals to match the max speed of the Corsairs (basically set it so they can't run at 100%)? Or is the difference small enough that I can have the same fan curve for each set?

Kleetz

I've not seen a CPU OPT header before; I ran a search and it seems it basically stands for "optional" and might be for plugging in the pump?

However, I took a look at the manual (chapter 1 - page 14) and from the looks of the table on page 1-14 it seems you might not be able to control them independently? Also, chapter 3 - page 7 & Chapter 3 page 8 of the manual only show one option for CPU, so you might want to look at that.

If it won't let you control the headers independently it might mean that it won't dial down the speed of the Fractal fans because both headers may (and to be honest, probably will) just default to PWM.

If that is the case you could run the fractal fans off of a case fan header at a consistent speed and run the PWM fans off of the CPU header as a kind of back up, for if you need more cooling power; kind of like an auxiliary/backup system for if/when the processor needs it?

Otherwise you could pick up some new PWM fans to replace the fractals and run those from the CPU OPT header, but that means more expense.

As for whether or not you should try and match the speeds, I wouldn't worry about that too much, I'd just go by noise and how well their combined cooling power is in relation to the noise they're generating, and just try and adjust them so that there's a balance between those two factors. Where the fan blades are physically, in respect to their orientation within the frame, won't affect the amount of area they're blocking, that doesn't change, it's just how many times per minute they scoop air and push it forward that determines how well they're performing. In other words, if you -- for example -- just unplugged one set of fans, there'd still be plenty of space between their blades not to cause an obstruction to the airflow. That changes with fan width, for high pressure fans (thicker fans are basically always higher pressure, that's why they're made thicker, to house expanded blades that cause obstruction/resistence so that air can't slip back through them).

But yeah, looking at the manual the pin out for the CPU & CPU OPT look identical so if you wanted to get another set of PWM fans you could probably split them off of the CPU OPT header, although to be honest, if it were me, and if I were going that route (and if the loop is for the CPU only, because it's only CPU temperature that's going to be taken into consideration by the motherboard in driving the pump off of that header), I'd use one of the adaptors linked to above and look into using the CPU OPT header for the pump. But you should probably research that, or maybe post another question here; I'm new to water cooling so flow rates are a little outside of my understanding.

In addition I have to say it surprises me that Asus don't give you greater control over the CPU OPT header.

EDIT: Sorry, just re-read and saw that the Fractals are 4-pin? I ran a search for them and found the 3-pin version, assumed that's what you had. But what I wrote should hopefully still cover the question?

 

[Kleetz]

Thanks,

Right, I can't control each fan independently, only as set or single, which is fine.

If you look at that page you linked to (chapter 1 page 14) you'll see that there is a dedicated AIO pump header off to the side (labeled D). That's where I have my AIO plugged into. The Corsairs fans are going to the CPU header (labeled A) and I have set their fan curve to Turbo in BIOS.

The BIOS doesn't show controls for CPU OPT, and I'll agree it's weird that there's no control. Maybe something needs to be plugged into it or maybe it takes on the same profile as the main CPU header?

I think CPU OPT will take the same profile as CPU. If I recall correctly, I plugged in a fan to that header when I was first testing things out and in BIOS for the CPU fan curve it plotted two curves. If so then I'll get a PWM splitter and run it off CPU OPT and run the Fractals into that and adjust it as needed.

My main concern now is power. Is it safe to say that CPU and CPU OPT are two separate headers and I won't be overloading them by plugging two separate PWM splitter into each running three fans a pop?

Thoughts?

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Man, I don't know how to edit in here!

EDIT:

Looking at the chart at the bottom of page 14, yes the CPU and CPU OPT headers share the same profile and each header has its own 1A power. So I think I'm good!

 

[GenkiM]

Thanks,

Right, I can't control each fan independently, only as set or single, which is fine.

If you look at that page you linked to (chapter 1 page 14) you'll see that there is a dedicated AIO pump header off to the side (labeled D). That's where I have my AIO plugged into. The Corsairs fans are going to the CPU header (labeled A) and I have set their fan curve to Turbo in BIOS.

The BIOS doesn't show controls for CPU OPT, and I'll agree it's weird that there's no control. Maybe something needs to be plugged into it or maybe it takes on the same profile as the main CPU header?

I think CPU OPT will take the same profile as CPU. If I recall correctly, I plugged in a fan to that header when I was first testing things out and in BIOS for the CPU fan curve it plotted two curves. If so then I'll get a PWM splitter and run it off CPU OPT and run the Fractals into that and adjust it as needed.

My main concern now is power. Is it safe to say that CPU and CPU OPT are two separate headers and I won't be overloading them by plugging two separate PWM splitter into each running three fans a pop?

Thoughts?

Oh wow, yeah, pump header, I missed that, lol sorry :embarrassed:

But yeah, try it with a PWM fan and see if it'll let you adjust the curves independently.

There is a benefit to running in push pull, although people will generally tell you there's not. If you look at radiator reviews it shows it definitely does make a difference to run push pull.

Again, as for matching speed, it would help to balance it for the push pull aspect but I'd personally recommend balancing noise to efficiency as (unless one's type is just super loud) that'll get the fans optimised anyway and should give you a more accurate measure of their optimisation.

Also, if you run multiples of the same make and model of fan it has a further noise damping effect because you can run them all slower and the sound waves cancel each other out to a certain extent. The drawback is you have more fans in your case and space might be an issue; also, you have to buy more fans, but personally I think the trade off is worth it (I'm what people tend to call a "silence freak")

I'd say it's a safe bet but that they're both independently powered. I'd be very very surprised if they weren't. But having said that, if you need your mind put at rest the best thing to do is ask, so maybe post to the Asus forums. That having been said I'd say it's almost an absolute certainty that they're separately powered. The manual rates them both at 1 Amp separately and to be honest it's probably trivial for them to add another fan header compared to overhauling the BIOS code so that you can run two CPU fan curves...

...I think if they both relied on the same power and split the 1 amp between them it couldn't be anything other than a design flaw and I'm sure Asus wouldn't let something like that happen.

Edit: Yeah, I'm sure it's fine. 99.9% sure

 

[GTXJackBauer]

I would recommend on using the same fans as one fan's spec is different from the others. It could create more turbulent airflow and therefore create more unneeded audibles. I could be wrong here but I think it could also push too much air to another fan and make it spin more than the motor wants too and possibly lessen the motor's longevity.

 

[Kleetz]

I would recommend on using the same fans as one fan's spec is different from the others. It could create more turbulent airflow and therefore create more unneeded audibles. I could be wrong here but I think it could also push too much air to another fan and make it spin more than the motor wants too and possibly lessen the motor's longevity.

Thanks! In the case of pushing too much air, the weaker fans (Corsairs) are going to be the push fans.

 

[Dermen]

It is kind of a pain but I would just test it with the RGB fans only, then test it with push/pull so you can get the exact difference and see if it is worth the added complexity/possible noise. With mismatched fans it is possible push/pull could end up being worse.

What case do you have and what fans? You might be better off putting the extra fans elsewhere in the system.

 

[Kleetz]

It is kind of a pain but I would just test it with the RGB fans only, then test it with push/pull so you can get the exact difference and see if it is worth the added complexity/possible noise. With mismatched fans it is possible push/pull could end up being worse.

What case do you have and what fans? You might be better off putting the extra fans elsewhere in the system.

Lian Li PC O-11 Dynamic. I currently have the AIO on the side with the Corsairs 120HDs pushing out and the Fractals that came with the AIO on top also pushing out.

Current temps are 29-30c idle and around 47-51c load.

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EDIT: I have the fans listed in the original post, so three Corsair HD120 and three Fractal Dynamic X2 GP-12

 

[Dermen]

That case has a lot of ventilation so that's good. It also has a ton of options. Doing push/pull will just give you 3x120mm size exhaust and no intakes. You might get better results with the 3 Fractal fans as air intakes, put them on the bottom of the case and your GPU might run cooler too with the fresh air blowing on it.