[SOLVED] Case Fan Config / Connectivity Advice For PC Newb Please

Jan 18, 2022
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Hi,

I'm looking to buy some case fans before I build my first PC. The case is an MSI MPG VeloxP Airflow and supports 3x 120mm or 140mm front fans, 3x 120mm or 2x 140mm top fans and 1x 120mm rear fan. The fans I have in mind are:
  • Be Quiet Light Wings 140mm PMW high speed ARGB (2200 RPM / 71.7 CFM / 0.4 A).
  • Be Quiet Light Wings 120mm PMW high speed ARGB (2500 RPM / 52.3 CFM / 0.45 A).
My research is suggesting I should go with the 140mm option, with a single 120mm at the rear but would like some confirmation or advice from experienced users on this or a better fan configuration.


My motherboard has 4x system fan headers, with the following pin configurations:
  • SYS_FAN1 & SYS_FAN2A: Ground, Voltage Speed Control, Sense, PMW Speed Control.
  • SYS_FAN2B: Ground, Voltage Speed Control, Sense, NC.
  • SYS_FAN_PUMP: Ground, Voltage Speed Control, Sense, PMW Speed Control.
I assume that SYS_FAN2B will not allow for PMW control over fans?
Is the SYS_FAN_PUMP a dedicated header for water cooling or can it be used for air fans too?


On a final note, my CPU cooler has 2 fans (Dark Rock 4 Pro), can I plug one each into the CPU_FAN & CPU_OPT headers or should I use a splitter for the CPU_FAN only?

All the fan headers have a maximum 2A current & 24W power rating so ideally I would like to spread the draw from my fans over these as much as possible.

Any help appreciated.
 
Solution
I could have opted for fans with a lower spec but I don't think there was much difference in price so I my thinking was that I have that extra power there if required in the future. However, if you say that fans don't run much below 50% then I'll have to consider that as well.
You generally want more/larger/slower fans. Go with the 1500rpm 140mm fans. In addition to not sounding like a jet engine at full speed, they also afford [pretty much guaranteed] operation into the ~900rpm which would be effectively silent for some/many workloads.

Is there something wrong with the 3x120mm (unlit) front intake fans and the 1x120mm ARGB rear exhaust fan that you'll get INCLUDED with the case? You want ARGB for everything and all fans to...
What CPU & GPU do you have?
2x140mm front intake, and 1x120mm rear exhaust would be a good place to start for an average system.

Go with 140mm fans anywhere you have the option.

2200 - 2500rpm is FAST. That's going to be LOUD if the fan(s) ever reach that speed. IMO, 1200rpm is ideal for quiet operation, 1500rpm is the max you'll want to tolerate. Keep in mind that a lot of fans won't run much below....50% of their max rated speed.
 
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Paperdoc

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You have not told us how many case ventilation fans you intend, and in which locations.

You also have not mentioned the concept of balance between intake and exhaust air flow capacity, so I'll deal with that first. To start with, what goes in MUST come out, so no matter what you do some air will flow through. Any imbalance between intake and exhaust will result in a small air pressure difference between the exterior (your room) and the interior of your case. This means that, at every small crack or hole, air will leak from the higher-pressure zone to lower. I prefer to have a small positive pressure INside the case so that air leakage flow outwards. Why? That prevents entry of room air containing dust. BUT that also means you MUST place dust filters at every fan intake point to prevent dust coming in there. Most cases come with some type of dust filter system (even if just a small screen mesh) at the common intake areas (e.g., case front) that you just need to clean from time to time. To accomplish a near-balance of intake and exhaust air flow capacity with a small bias towards more intake capacity, you can START with the number of case fans and their total max air flow ratings, but this is NOT a complete picture. IF you are using a liquid-cooled CPU cooler and rad they become part of this, but YOU are not doing that, OP. However, the dust filters on the intake fans do reduce their real air flow impact to less than their max rating, so exactly matching numbers of intake and exhaust fans does NOT get you the right balance. In my view, the ideal would be slightly less exhaust capacity rating to offset the small reduction of intake from the dust filters. For your specific case, my "ideal" might be three 140 mm front intakes, two 140 mm top exhausts, and one 120 mm rear exhaust. Intake fans' total max air flow exceeds exhaust fans' total max by ratings, so we expect that the small impact of the front fans' dust filters will still leave a slight positive pressure inside your case. For the two TOP exhaust fans, mount them to the REAR of the case as much as your case allows (you may not have any choice there) to avoid having an air flow "short circuit" inside the top front corner of your case.

Now, that's a lot of case fans - six in total. How would you connect them to your headers? We'll look at those case fans only for now, and you really have two headers for them: SYS_FAN1 and 2A. The 2B one should not be used for PWM fans unless you need to, and you do not need to. The PUMP fan header MAY be used for fans - depends on whether your mobo allows a setting for this, and we can't see that detail. The critical item here is the max CURRENT capacity of each header. Most are 1.0 A, but you say yours are rated for 2.0 A max each. Check that to be sure. Assuming you are correct, you can use simple Splitters like this

https://www.amazon.com/Cable-Matters-2-Pack-Way-Splitter/dp/B07PXLHNZ6/ref=sr_1_4?crid=2ZOG5ZKQ1JLXF&keywords=fan+splitter&qid=1644956401&sprefix=fan+splitter,aps,98&sr=8-4

That is a 2-pack of 4-pin Splitters with 3 output arms each. NOTE that a Splitter has one input that plugs into your mobo SYS_FAN header, and two (three in this case) arms for plugging in fans, but NO other arm types. A HUB is a different device that also has a third type of "arm" that must plug into a SATA power output from the PSU for extra power. You do not need that here as long as your headers can deliver up to 2 A per header. The fans you are considering say (in their spec sheets) their max current draw for their MOTORS is 0.38 A per 140 mm fan, or 0.45 A for the 120 mm unit. So three fans together can draw at max 1.21 A, more than a typical header can do but well within the specs for your mobo headers. So, you can group three front intake fans together on one header, and the three exhaust fans on the other. Configure both headers exactly the same so they all do the same thing. (Current draw by the LIGHTS in each fan is not part of this because lights are powered and controlled separately from motors.)

If you think that six fans total is overkill, I suggest you just cut back to two on the front (bottom and centre) and one on the top rear, and still the one 120mm at rear - total 4 fans - and still use two Splitters on the two headers.

A couple points of interest FYI regarding Splitters etc. Each fan generates a speed signal consisting of a train of pulses sent back to its mobo header on Pin #3. The header counts these pulses, but it cannot handle more than one fan's pulse stream. So any Spltter will send back to its host header the speed signal from only ONE of its fans and ignore the rest. The easiest way to do that is NOT to include Pin #3 on most of the output arms. When using s Splitter, make sure one of your fans IS plugged into the only output with ALL FOUR of its pins, so that that fans's speed can be returned to the host header. Now, a secondary function of a header is to monitor the speed signal for fan FAILURE and warn you of that if it happens. It can not do that for the "extra" fans on a Splitter whose signals are not reported. So from time to time YOU should check that all your fans are working.

Regarding your CPU cooler system with two fans, I recommend you connect them both to the CPU_FAN header. The kit includes one 2-output Splitter for this purpose.
 
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If air cooled and not heavily overclocked, you aren't likely to need 6 or 8 fans.

In my experience, that "sys fan pump" connector would have the same functionality as the other PWM connector. That's the way it is on my motherboard.

Look in your motherboard manual for any indication that is not so.
 

Paperdoc

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For that pump connector, look in the mobo manual for the BIOS Setup options for that header. If it has an option to specify whether it is to be used as a FAN header or a PUMP header, that is what you need. A header that is usable ONLY for a PUMP has NO ability to control any fan speed - it is designed to give full power at all times. If you can configure it to be a FAN header, then you have that control ability on that header.
 
Jan 18, 2022
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Thanks all for the replies, there's some good info for me to think about.

What CPU & GPU do you have?
2x140mm front intake, and 1x120mm rear exhaust would be a good place to start for an average system.

Go with 140mm fans anywhere you have the option.

2200 - 2500rpm is FAST. That's going to be LOUD if the fan(s) ever reach that speed. IMO, 1200rpm is ideal for quiet operation, 1500rpm is the max you'll want to tolerate. Keep in mind that a lot of fans won't run much below....50% of their max rated speed.
CPU: i5-12600K (not looking to OC just yet but that will likely change in the future).
GPU: Gigabyte Aorus Master 3070 Ti.

I could have opted for fans with a lower spec but I don't think there was much difference in price so I my thinking was that I have that extra power there if required in the future. However, if you say that fans don't run much below 50% then I'll have to consider that as well.


You have not told us how many case ventilation fans you intend, and in which locations.

You also have not mentioned the concept of balance between intake and exhaust air flow capacity, so I'll deal with that first. To start with, what goes in MUST come out, so no matter what you do some air will flow through. Any imbalance between intake and exhaust will result in a small air pressure difference between the exterior (your room) and the interior of your case. This means that, at every small crack or hole, air will leak from the higher-pressure zone to lower. I prefer to have a small positive pressure INside the case so that air leakage flow outwards. Why? That prevents entry of room air containing dust. BUT that also means you MUST place dust filters at every fan intake point to prevent dust coming in there. Most cases come with some type of dust filter system (even if just a small screen mesh) at the common intake areas (e.g., case front) that you just need to clean from time to time. To accomplish a near-balance of intake and exhaust air flow capacity with a small bias towards more intake capacity, you can START with the number of case fans and their total max air flow ratings, but this is NOT a complete picture. IF you are using a liquid-cooled CPU cooler and rad they become part of this, but YOU are not doing that, OP. However, the dust filters on the intake fans do reduce their real air flow impact to less than their max rating, so exactly matching numbers of intake and exhaust fans does NOT get you the right balance. In my view, the ideal would be slightly less exhaust capacity rating to offset the small reduction of intake from the dust filters. For your specific case, my "ideal" might be three 140 mm front intakes, two 140 mm top exhausts, and one 120 mm rear exhaust. Intake fans' total max air flow exceeds exhaust fans' total max by ratings, so we expect that the small impact of the front fans' dust filters will still leave a slight positive pressure inside your case. For the two TOP exhaust fans, mount them to the REAR of the case as much as your case allows (you may not have any choice there) to avoid having an air flow "short circuit" inside the top front corner of your case.

Now, that's a lot of case fans - six in total. How would you connect them to your headers? We'll look at those case fans only for now, and you really have two headers for them: SYS_FAN1 and 2A. The 2B one should not be used for PWM fans unless you need to, and you do not need to. The PUMP fan header MAY be used for fans - depends on whether your mobo allows a setting for this, and we can't see that detail. The critical item here is the max CURRENT capacity of each header. Most are 1.0 A, but you say yours are rated for 2.0 A max each. Check that to be sure. Assuming you are correct, you can use simple Splitters like this

https://www.amazon.com/Cable-Matters-2-Pack-Way-Splitter/dp/B07PXLHNZ6/ref=sr_1_4?crid=2ZOG5ZKQ1JLXF&keywords=fan+splitter&qid=1644956401&sprefix=fan+splitter,aps,98&sr=8-4

That is a 2-pack of 4-pin Splitters with 3 output arms each. NOTE that a Splitter has one imput that plugs into your mobo SYS_FAN header, and two (three in this case) arms for plugging in fans, but NO other arm types. A HUB is a different device that also has a third type of "arm" that must plug into a SATA power output from the PSU for extra power. You do not need that here as long as your headers can deliver up to 2 A per header. The fans you are considering say (in their spec sheets) their max current draw for their MOTORS is 0.38 A per 140 mm fan, or 0.45 A for the 120 mm unit. So three fans together can draw at max 1.21 A, more than a typical header can do but well within the specs for your mobo headers. So, you can group three front intake fans together on one header, and the three exhaust fans on the other. Configure both headers exactly the same so they all do the same thing. (Current draw by the LIGHTS in each fan is not part of this because lights are powered and controlled separately from motors.)

If you think that six fans total is overkill, I suggest you just cut back to two on the front (bottom and centre) and one on the top rear, and still the one 120mm at rear - total 4 fans - and still use two Splitters on the two headers.

A couple points of interest FYI regarding Splitters etc. Each fan generates a speed signal consisting of a train of pulses sent back to its mobo header on Pin #3. The header counts these pulses, but it cannot handle more than one fan's pulse stream. So any Spltter will send back to its host header the speed signal from only ONE of its fans and ignore the rest. The easiest way to do that is NOT to include Pin #3 on most of the output arms. When using s Splitter, make sure one of your fans IS plugged into the only output with ALL FOUR of its pins, so that that fans's speed can be returned to the host header. Now, a secondary function of a header is to monitor the speed signal for fan FAILURE and warn you of that if it happens. It can not do that for the "extra" fans on a Splitter whose signals are not reported. So from time to time YOU should check that all your fans are working.

Regarding your CPU cooler system with two fans, I recommend you connect them both to the CPU_FAN header. The kit includes one 2-output Splitter for this purpose.
Thanks for the details, some of this I'm aware of, like pressure, but you have provided some nice advice on what to consider to achieve the right balance.

Perhaps it wasn't clear from my post, but I was thinking of using the maximum amount of fans supported by my case and it seems I can get away with only using two fan headers even with that configuration.

As for splitters, I think the fans I'm considering come with a hub, but I'm not sure if this is for the fans themselves, the ARGB or both. You suggest not to use pin #3 on some fans, how do I go about doing this? Can it be deactivated in BIOS settings or would I have to physically break it off? I wouldn't be comfortable with the latter method, particularly if you say the headers ignore extra signals. I assume using a splitter would mean all fans attached to it would run at the same RPM?


If air cooled and not heavily overclocked, you aren't likely to need 6 or 8 fans.

In my experience, that "sys fan pump" connector would have the same functionality as the other PWM connector. That's the way it is on my motherboard.

Look in your motherboard manual for any indication that is not so.

For that pump connector, look in the mobo manual for the BIOS Setup options for that header. If it has an option to specify whether it is to be used as a FAN header or a PUMP header, that is what you need. A header that is usable ONLY for a PUMP has NO ability to control any fan speed - it is designed to give full power at all times. If you can configure it to be a FAN header, then you have that control ability on that header.

OC'ing isn't something I'm going to do yet, but likely will in the future. In the meantime will using many fans still have some benefit? One situation I want to avoid is reducing the number of fans in my initial build only to find out that they aren't enough and having to remove any components to fit them. Would installing them in the case and leaving them dormant by not connecting them to the motherboard be a viable option?

I did not see anything in my manual about the fan pump header's functionality but I wasn't looking for that info so will look again, although judging by other replies it may be that I won't have to use that header anyway.

A couple of additional question I have just thought of:
Should I go for pressure fans or airflow fans, or even a combination of both?

Is it better to orientate my CPU cooler so the air flow is directed to the rear / top exhaust fans?

It seems that most of my original questions have been addressed so thanks once again but please do feel free to add anything else, particularly in response to any additional info or any additional questions I have given in this reply.
 
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I could have opted for fans with a lower spec but I don't think there was much difference in price so I my thinking was that I have that extra power there if required in the future. However, if you say that fans don't run much below 50% then I'll have to consider that as well.
You generally want more/larger/slower fans. Go with the 1500rpm 140mm fans. In addition to not sounding like a jet engine at full speed, they also afford [pretty much guaranteed] operation into the ~900rpm which would be effectively silent for some/many workloads.

Is there something wrong with the 3x120mm (unlit) front intake fans and the 1x120mm ARGB rear exhaust fan that you'll get INCLUDED with the case? You want ARGB for everything and all fans to match?

Also, why the BeQuiet Light Wings? They "only" have a LED ring around the outside.

You're unlikely to see additional gains beyond 3x140mm front intake, 1x120mm rear exhaust, 1x140mm top exhaust.
 
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Jan 18, 2022
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You generally want more/larger/slower fans. Go with the 1500rpm 140mm fans. In addition to not sounding like a jet engine at full speed, they also afford [pretty much guaranteed] operation into the ~900rpm which would be effectively silent for some/many workloads.

Is there something wrong with the 3x120mm (unlit) front intake fans and the 1x120mm ARGB rear exhaust fan that you'll get INCLUDED with the case? You want ARGB for everything and all fans to match?

Also, why the BeQuiet Light Wings? They "only" have a LED ring around the outside.

You're unlikely to see additional gains beyond 3x140mm front intake, 1x120mm rear exhaust, 1x140mm top exhaust.
There's nothing 'wrong' with the fans included with the case, it's just that I would prefer 140mm PWM fans, ARGB isn't a top priority for me, just a nice aesthetic touch. The Light Wings seemed to fit the criteria which I was looking for and I've only heard good things about them.

You suggest 3x 140mm front intake fans, 1x 120mm rear exhaust fan & 1x 140mm top exhaust will be adequate, won't this setup produce too much positive pressure inside the case, or should that not be too much of a concern?

Do you have any advice about the two questions I added to the end of my previous post?
 
There is no substitute for trial and error. There are too many unknown variables that would pertain to your specific situation. Ambient temps, your sensitivity to noise, your anxiety levels over a temp of X; individual case peculiarities, typical load on the CPU, and on and on.

So be prepared to do that.

Generally.....you want higher pressure fans blowing into the more restricted areas...such as into the fins of a heat sink. The Noctua F12 would be an example, whereas the A or S series would be more suitable where there is less restriction, such as for a typical dust filter on the intake side or as a standard exhaust fan.

Noise level aside, it's entirely possible the fans included with the case will be fine. I wouldn't buy additional fans unless and until I was unsatisfied with them and you can't know that before you experiment.

Fans above 1000 rpm will gradually become audible. Maybe that doesn't bother you.

Some people will go to considerable lengths to get a 50 degree temp reduced to 45, as if it were a contest. If you are like that, you can find yourself fiddling with cooling endlessly.

For a standard tower case, you'd normally orient the CPU cooler fan to blow through the heatsink to the rear...toward the rear exhaust vent.
 
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You suggest 3x 140mm front intake fans, 1x 120mm rear exhaust fan & 1x 140mm top exhaust will be adequate, won't this setup produce too much positive pressure inside the case, or should that not be too much of a concern?
As was mentioned previously, positive pressure is preferable because that means all the air coming into the case is through the fans (which are preferably filtered to reduce dust buildup inside the case). As far as too much....keep in mind that you're counting CFM and CFM relies on RPM. Running the fans at less RPM reduces their CFM so you can balance pressure that way if you like.

Is it better to orientate my CPU cooler so the air flow is directed to the rear / top exhaust fans?
Rear.

Should I go for pressure fans or airflow fans, or even a combination of both?
You generally want to use "airflow" fans in cases and "pressure" fans on radiators. Air coolers generally tend to have a low fin density, so airflow fans can work well there also.
 
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Paperdoc

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A few further points to help.

The HUB that comes with a 3-pack of those Be Quiet Light Wings 140mm PMW high speed ARGB fans is for the ARGB LIGHTS in the frames only. Many mobos have only one ARGB lighting header, so providing that Hub solves the user's issue of how to connect 3 to 6 lighting devices to that one mobo header. On the other hand, a similar issue for the MOTORS of all those fans is readily available from a combination of several mobo headers and the use of either Splitters or a fan motor Hub.

About fan pressure ratings. The published specs for fans work this way as far as I can tell. All the ratings are for when the fan is operating at max speed. Air FLOW rating is what will be delivered if there is NO resistance to air flow. But as more resistance is provided (items in the air flow path that interfere), actual air flow delivered is reduced as the backpressure is increased. At some backpressure value the effective air flow created drops to zero. So a graph of backpressure versus air flow looks ROUGHLY like a straight line from zero airflow at the (max) backpressure rating, on to max airflow rating at zero backpressure. These parameters depend primarily on the design of the fan blade system, but certainly there is a impact of fan speed, too. The general result for similar fans operating at the same max speeds is that "Flow" fans are designed to give higher air flows than "Pressure" fans at little backpressure (typical for case ventilation). "Pressure" fans can still blow MORE air flow against the types of air flow resistance that result from finned heat exchangers and radiators, so they are suited to CPU air coolers AND the radiators on AIO cooler systems.

Similarly, noise ratings are the max noise created when the fan is running full speed. In actual use, what happens, of course, is that the automatic fan control system (IF you use that) reduces the speed of the fan according to the actual TEMPERATURE measured by a sensor. (For the CPU chip, this is a sensor built into the chip itself; for the case ventilation fans, the SYS_FAN headers should be guided instead by a temp sensor in the mobo.) The fans are run only at whatever speed is necessary to deliver the right amount of heat removal - that is, AIR FLOW - at any time. So, although a high-speed fan may make more noise and generate higher air flow at max speed, it will still generate much LESS noise when run at LOWER speed to deliver a certain air flow rate. If you want to compare the actual noise of two fans with different published ratings when they are run at whatever different speeds are required to produce identical air flows, you need extensive data that you will never find published. So it's anyone's guess whether a fan designed for slower max speed and less max noise will really be quieter than a high-speed fan running slower. So what other factors should you consider? One is: what is the real minimum speed, and is that really quiet so you can accept that? Probably yes. What is the advantage of a high-speed fan? Reserve capacity! That is, if your system is run at very high workloads producing a lot of heat requiring removal, a high-speed fan able to provide high air flows can keep up with that heat removal load, probably more than you'll ever need, whereas a lower-speed fan may not be able to handle those extreme conditions. The downside of this is the opposite end of the heat load situation - low workload and minimum air flow required, so fans running at their minimum speed. In that situation your fans MIGHT actually be over-cooling because the minimum air flow they deliver is more than required, but that is probably OK. In that situation the noise being generated may be a bit higher from the high-speed fan designs, but it still will be quite low.

About pins and speed signals. YOU do not have to do ANY modifications. Splitters are made that way already when you get them - that is, the Splitters that look like groups pf cable "arms" - and that applies also to Hubs of this appearance. Splitters and Hubs both also can look like small circuit boards with male ports on their edges, or like closed boxes with ports recessed inside holes. On those designs the male ports all have all their pins, but the circuit board simply does not make any connection to Pin #3 of most ports. Then there is ONE output port identified by label as the only one that WILL relay its fan's speed signal back to the mobo host header. In all cases they are made that way and require no intervention by the user.

Aiming the CPU cooler? Yes, position so it discharges toward the rear or top exhaust areas.

Setting up for good total air flow plus a balance of intake and exhaust flow capability is best done now at the design stage, based mainly on the fan max specs and fan count. When it's all done, installed, and working to your satisfaction, you MAY decide to try to optimize. To do this you need a testing procedure - a smoke tracer technique. You need a small source of smoke - either a smouldering incense stick or a cigarette. Get your system running, typically at idle conditions. Move your smoke source around the outside of your case close to small cracks and leak spots, and observe the way the smoke moves. If it drifts AWAY from your case at those spots, you have a small internal positive pressure and air leakage is outwards. That is ideal. If the smoke is drawn into your case, you have the opposite condition. If it moves really fast, you have a large imbalance. Repeat this test with a couple of different workload conditions.

If you decide that results warrant some adjustment, you may be able to do that with your mobo's SYS_FAN headers. This is easier if the groups of fans you have established using Splitters and headers are separate intake and exhaust groups, so you can adjust each group independently. Most mobo headers are set to use a default Profile called "Standard" or "Normal" that uses a re-defined "Fan Curve" of speed to run the fans versus measured temperature. Most also offer another option that allows you to re-specify the details of that curve at four or five points. IF you need to make adjustments, you can change to this user-defined Profile curve for one or both headers, and create your ideal pressure balance over a range of heat loads.
 
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Hi all,

Thanks once again for your input, I think I have plenty of advice to enable me to decide which fans and config to go with as well as some additional advice to help with other things along the way.