Question about adding fans to my system - need advice

You can fan header splitter to install more fans than you have headers. Or get a fan hub or a fan controller - http://pcpartpicker.com/product/dQ8Zxr/nzxt-fan-controller-acsen3b1 or http://pcpartpicker.com/product/tWW9TW/nzxt-fan-controller-senmix2

Edit: Or you can get NZXT Grid+ V2 if you want to mount the controller inside the case - http://www.newegg.com/Product/Product.aspx?Item=N82E16811992015

OK, so I'm intrigued with details as posted. You have a case that comes with 4 fans pre-installed, and includes two separate fan control knobs on the top front - one each for two fan groups. I expect those knobs each give you options to set the fans MANUALLY to Off / Low / High. That certainly does not give you automatic control of the pre-installed case fans by the mobo. Now, you also say that all of your mobo's fan headers are fully in use - that's three of them. So, what fans are plugged in to those? Is it the three pre-installed ones (top, front, and back) that you do NOT plan to replace?

I ask because most cases with that system - pre-installed fans connected to a front switch - are using basic 2-wire fans whose speed can ONLY be controlled by changing the voltage supplied to them. That's what those Low / High switches do, and that's what a mobo fan header in Voltage Control Mode would do. BUT you do NOT have that type of mobo fan header! The type you have are called 4-pin headers that operate in PWM Mode, and they can only control the speed of a 4-pin PWM style fan. So unless you are replacing all of the pre-installed fans with 4-pin fans, I expect your mobo headers can only run them at full speed all the time, which is even less flexible than using the original two-speed switches.

Now, there is a way to apply automatic control from the mobo fan headers to 3-pin fans and 2-pin fans using a particular Fan Hub. So, if that is what you intend - control the pre-installed fans with 2 wires from each using the mobo fan headers - post back here for detailed advice (see the end).

Now, setting aside that point I'll get back to your original quest - how to power and control 4 new 4-pin fans from some place, using mobo automatic control. This will require a proper 4-pin Fan Hub and use of one of your existing mobo SYS_FAN headers.

First, let me explain splitters and hubs, and it can be confusing because I see many on-line seller sites that use the two terms wrongly. A SPLITTER simply connects the Ground and DC Voltage lines from two or more fans together and then to the pins of a connector that plugs into the mobo header. Now, a little more detail which depends on whether the fans are 3-pin or 4-pin. Both types send a signal generated in the fan motor back to the mobo header on Pin #3 so the mobo can measure and display the fan speed, but this signal is NOT actually needed for control of the fan. Moreover, a mobo header can only accept such a signal from ONE fan, so any decent splitter only sends back the speed signal from ONE of its fans, and ignores the rest. Next, the 4-pin thing. 4-pin fans work differently. They do not receive variable voltage from Pin #2 as 3-pin fans do. They receive a fixed 12 VDC on Pin #2,and then the extra PWM signal on Pin #4. Inside the motor is a chip that uses the PWM signal to control how much power actually runs through the motor. So the control signals from the mobo header must match the capabilities of the fan connected for speed control to work. Now, BOTH types of mobo fan headers have a limit of about 1 amp total current to the fans plugged into each one. So you can use a splitter to connect two or three "regular" fans together to one mobo fan header, and MAYBE even four or five if they have modest power pulls.

A Fan HUB works differently. It draws the control signal for its fans from a mobo fan header and returns to that header the speed signal of one fan. But for POWER to all its fans it gets that from the PSU directly, by connecting to a power output designed either for SATA devices or for the older IDE devices. This latter type of output is often called a 4-pin Molex output, or a Peripheral power output. Those outputs from the PSU have a MUCH larger current supply capability so you can run MANY fans from one of them. The trick is control! That type of power supply is fixed at 12 VDC, so you cannot control 3-pin fans from it, because 3-pin fans can only be controlled by reducing their supply voltage. However, 4-pin fans all require that fixed 12 VDC supply on Pin #2, and rely on the special added PWM signal on Pin #4 to achieve speed control. The design of the circuits involved means that connecting many fans to one source of PWM signal is OK, unlike the situation for the DC supply power. So you CAN have a 4-pin fan system Hub that draws power from the PSU, and simply shares the PWM signal from one mobo SYS_FAN header to all the fans plugged into the Hub. But this only works if the mobo header actually does use PWM Mode for control (yours does, OP) AND the fans you use are of the 4-pin type (those Noctua fans you linked are that type).

So, how do you apply this to your needs? First, you will need a real 4-pin fan Hub, not a splitter. One like this will do it:

http://www.newegg.com/Product/Product.aspx?Item=9SIA7B446G3570&cm_re=fan_hub-_-11-999-309-_-Product

It has eight output ports, one female 4-pin fan connector to go to one mobo SYS_FAN header, and one power connector to go to a PSU SATA power output. This raises two issues. One is that all your mobo SYS_FAN headers are in use already. Well, unplug a fan from one, use that header for the Hub's source, and plug the disconnected fan into one of the Hub's ports. The other is the power connection. If you don't have an unused SATA power output, you can use one of the Peripheral outputs and an adapter like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16812422771&cm_re=adapter_Molex_to_SATA-_-12-422-771-_-Product

(By the way, be cautious as you use the "Perif" cable from your modular PSU. Many such cables have two or three standard 4-pin Molex female outputs, plus a much smaller one on the end. That small one is for one purpose only - to supply power to a 3½" floppy drive, which I BET you do not have. So do NOT connect that to anything.)


When you connect fans to the Hub, note that one is marked off separately. THAT is the only fan on the Hub that will have its speed signal sent to the mobo SYS_FAN header for measurement.

Now, that will get you power to all four Noctua 4-pin fans plus to one other fan that you've already plugged into one SYS_FAN header. We still have that issue I started with: what are those fans you already plugged in? If they are the original pre-installed case fans I expect their speeds can NOT be controlled by those SYS_FAN ports or by the Hub, and they will all run full speed when connected to your SYS_FAN headers that only operate in PWM Mode. IF that is true, and IF you want to get ALL those case fans under mobo control, there is a way. You just need to buy and use a different 4-pin Hub that is able to control BOTH 3-pin and 4-pin fans. AND (if you have not dealt with this already) you MAY need to arrange for connectors on those fans that work like normal 3-pin fan connectors.

SO, if you need details of that last bit - getting ALL fans under control - post back here.

Great, that helps clarify. It leaves some questions unanswered, though.

First, since you have all four case fans now connected to mobo fan headers, I have to assume you found how to make those connections. MAYBE each of those fans has a standard female 3-pin fan connector on the end of its wires? Now, how many wires come out of each fan's motor to the connector? The "standard" case fan wiring has a Black wire to connector Pin #1 for Ground, a Red wire for DC supply voltage to Pin #2, and a Yellow wire for the speed signal to Pin #3. Is that what yours have, or something different?

I also note that the front fan, according to the case maker, has a switch to allow you to turn on or off its LED light. Where is that switch? Is it on a separate cord attached to the fan? FYI, may such fans that don't have any switch just feed the LED's from the DC supply the motor gets. Now, the motor uses up to 12 VDC, but the LED's only need 5 VDC for full brightness. So the LED's work just fine at most fan speeds, but get a bit dim when the fan is running very slow.

Related question: how do you plug 4 fans into 3 mobo SYS_FAN headers? Are you already using one Y-splitter? Or, is one of those plugged into the mobo CPU_OPT header? If that is the case, it's not quite ideal, but that's easy to change. You see, the SYS_FAN headers base their control on the temperature measured by a sensor in the mobo. The CPU_FAN and CPU_OPT headers base control instead on a sensor built into the CPU chip itself, so that system is not quite as good for CASE fan ventilation control as the SYS_FAN headers are. But to change is easy. If you install a 4-pin Hub, you can connect TWO of the current four case fans to that Hub as well as the four new ones. This make two case fans on two SYS_FAN headers, two plus the new four on the Hub, and the Hub has one SYS_FAN header to connect to.

Now, your concern about loading the headers etc. Your concern is well-founded. If you were to connect all those fans using splitters to the three SYS_FAN headers, you night risk overloading those headers. This is precisely why I said you MUST use a 4-pin HUB and not a splitter. A Hub draws all the power for its fans directly from the PSU through its connection to a SATA or Molex output. Thus it does NOT put any load on the mobo header it connects to. The header connection does only two functions: it returns one fan speed signal to the mobo, and it picks up the PWM signal from Pin #4 to share out to all its fans. The fan circuits that use that one control signal do not pull appreciable power from the mobo, so that does not overload the SYS_FAN header.

Now, we still have an important unanswered question: can the mobo SYS_FAN headers control the speed of your pre-installed case fans, or do they only run full speed all the time? The way I understand it, those pre-installed fans are very UNlikely to be 4-pin fans with 4 wires from their motors to their connectors. And 4-pin fans are the only type that your SYS_FAN headers can control. It sounds like you already have your system assembled and running, so do this observation carefully. Open your case and then start up the computer, observing those fans immediately. There are two possibilities for those case fans. IF they are under control, they all will start up at full speed for a few seconds, then slow down because the system temperature is low. After that as you do work, they may speed up a bit as temperatures rise. BUT what I really expect is that instead, they all start up at full speed and stay that way all the time. If that is the case, then those fans cannot be controlled by any 4-pin system using PWM control, and a different system is needed. So, post back what the fans really do.

IF those fans run full speed all the time, the "fix" is simple. I linked you to a Silverstone 4-pin Hub earlier, and hinted at a different one. There is another type called the Phanteks PWM Hub, here:

http://www.newegg.com/Product/Product.aspx?Item=N82E16811984004&cm_re=Phanteks_PWM_Hub-_-11-984-004-_-Product

Like other Hubs it draws all power for its fans from a SATA output of the PSU, and connects to one mobo SYS_FAN header for its PWM control signal. But is has one difference that is important to you, OP. It does not merely share that PWM signal to 4-pin fans. It uses the signal internally to create its own group of 3-pin fan ports operating in Voltage Control Mode, which is what you need to control the speed of 3-pin (or 2-pin) fans. It has six ports on it, but like common mobo ports each of those can handle up to 1 amp load. So it CAN be used with Y-splitters to connect two fans to each port (except Port #1), so it can handle up to 11 fans that way. It even comes with two splitters, so it can handle eight fans out of the box.

This Phanteks PWM Hub makes use of a backwards compatibility feature in case fans. The connector and wiring of 3-pin and 4-pin fans are designed so that you can plug any female fan connector into any male output port and it will fit. The connectors have a tongue and groove molded into them so you can only plug them in the right way. Plugging a 3-pin fan into a 4-pin port gets you a fan that runs full speed all the time with no speed control. BUT plugging a 4-pin fan (your Noctuas) into a 3-pin port (on this Hub) DOES result in a fan running under full control. From an electrical perspective, this type of mis-match is not completely ideal, but the difference is small an does not matter for your use. So this Hub can power and control any mix of 3-pin and 4-pin fans.

Now, like any other 4-pin Hub, this Hub can only work if the mobo header it plugs into is truly a 4-pin header that operates in PWM Mode and thus provides a PWM signal on its Pin #4. Your mobo does it this way, and the proof of that will be in the speed test above: if your existing fans can only run at full speed off the mobo headers, they are true 4-pin headers. But the Phanteks instruction sheet tells you to do things a bit differently because some mobos do it oddly. They use headers with 4 pins, but operate them like 3-pin headers with a useless 4th pin, failing to provide the PWM signal. Just in case you have that type of mobo, the Phanteks instructions tell you to connect their Hub ONLY to the CPU_FAN header (which always is a true 4-pin type) and then connect your real CPU cooler to the Hub on Port #1. You should NOT do it that way. Leave your CPU cooling system connected to the CPU_FAN header. Plug the Phanteks Hub into one of the SYS_FAN headers because your mobo DOES provide the required PWM signal on Pin #4. Ensure that one of your new 4-pin Noctua fans is plugged into Port #1 (white) of the Hub so that it gets a fan speed signal to send back to the mobo. Then plug all the rest of your case fans - all the 3-pin pre-installed ones plus all the 4-pin Noctuas - into the Hub's ports, using a supplied splitter to get 7 fans on 6 ports. When you do this and observe the fans at start-up, they should all follow the pattern of starting fast, then slowing down.

Re: the choice of Noctuas. The 3000 rpm fans blow 50% more air at full speed, but to do that they use three times as much power! My guess is that, with three pre-installed fans plus four of the 2000 rpm Noctuas on the side you will have plenty of air flow and cooling, and will not need the extra that the higher-power fans can provide. So, I'd go with the 2000 rpm model. They are quieter at max speed, BUT I don't know what noise is generated by the 3000 rpm model when it is slowed down to generate the max airflow you can get from the slower fan. IF you think you want the "insurance" of having too much cooling potential and letting the fan run slower for normal uses, get the 3000 rpm models. That MIGHT give you something of an imbalance, though. Those four Noctuas in the side panel will blow a lot of air and deliver significant cooling of the mobo. That means the automatic control system will slow them down to achieve the right temperature, with the result that the three pre-installed fans at front, top and back also will slow down, probably delivering less air from those sources than the Noctuas deliver.

By the way, just thought of something. Check the direction of air flow on each fan. With the arrangement you plan, the front and 4 side Noctuas should blow into the case, and the top and rear pre-installed fans should blow out. I expect that is how the three pre-installed units are mounted already, but just check.

Now, the choice of which Hub to get is based on this: you do NOT have any way to control the speed of your three pre-installed fans (with 3 wires and pins) with your mobo. All its SYS_FAN headers operate in PWM Mode, and 3-pin fans need Voltage Control Mode for control. So with the Silverstone unit no matter how you connect things, those three pre-installed fans will always run full speed. If you return it and get the Phanteks PWM Hub, it CAN control both 3-pin and 4-pin fan speeds so you can have all your fans under control automatically by the mobo.

If you get the Phanteks hub you will not need to buy ANY splitters. By the way, that last item you linked is a perfect example of the "confusion" in product naming I mentioned. Look closely and you will see it has NO connection to a PSU to get fan power. It draws ALL power for its fans from the mobo 4-pin header it is plugged into, so it is just a 4-pin splitter (with three outputs instead of two).

Anyway if you get the Phanteks unit instead you will have six Hub ports for 7 fans. BUT the Phanteks unit comes with two 3-pin Y splitters, allowing you to connect two fans each to two of the Hub's ports. Now you're up to a capacity to connect 8 fans without buying extra items. Well, you do need one extra. You said from the beginning that all your PSU power outputs are in use already, and so I presume that means you have no unused SATA power output connector to plug the Phanteks Hub into. In that case you need that little adapter I linked to before:

http://www.newegg.com/Product/Product.aspx?Item=N82E16812422771&cm_re=adapter_Molex_to_SATA-_-12-422-771-_-Product

This will convert a 4-pin Molex (aka Perif) connector from that spare cable from your modular PSU into another SATA power output connector that you can use to plug in the Phanteks Hub.

When you install the Hub with one of its included splitters and all seven fans, the Hub's connection to the mobo for control will be to only ONE of your SYS_FAN headers, leaving the other two unused.

You are welcome, and thanks for Best Solution. Let us know how it goes.

First question: What mobo header do you have the Phanteks PWM Hub's 4-pin fan connector plugged into? If all of your case ventilation fans are connected to that Hub, then only one of those fans will have its speed forwarded to the mobo for display. That ONE fan with its speed displayed will be the one plugged into Hub Port #1 (the white one). All other Hub-controlled fans will have their speed ignored. Moreover, that one speed will be reported and displayed according to the mobo header you plugged into. That should be one of the three SYS_FAN headers. But did you plug the Hub into some other header? If you did, that would explain why no fan seems to be reporting through the SYS_FAN headers.

Second point: sometimes these third-party system monitoring utilities are tricky because they need to be custom-configured to your mobo. It may be simpler to do what you want in terms of monitoring and display to use the free utility supplied by Gigabyte on the CD that came with the mobo. It has drives and a whole bunch of utility software - see manual p. 84, Item 4-2, plus item 5-2 on p. 89 for info on finding and installing. The specific tool within the App Center I'm referring to is called System Information Viewer - see Item 5-2-2 on p. 91. It has a screen for Smart Fan Auto which sets automatic fan controls. If you can't find the info you seek there, try the Smart Fan Advance screen, but in there I don't recommend that you make any changes - the default automatic settings should do nicely for now.