Last Updated on November 6, 2020
If your current exhaust fans aren’t adequate for your needs then, it may be time for you to add more. However, motherboards have a limited number of fan headers. So, exactly, how to connect extra fans to the motherboard?
If you want to add extra case fans, you’ll have to get pulse-width-modulated (PWM) Y splitters that allow for multiple fans to be connected to a single fan header. Be warned, however, that most headers are limited to just 1 Ampere (A) and going beyond this is not advisable.
It is quite important to check the fans’ amperage since it will be the determining factor on how many of such fans you can actually run off the motherboard. For instance, you can only run two 0.5A fans while four wouldn’t be an issue for 0.23A fans.
A workaround would be PC fan hub that can draw power directly from the power supply unit (PSU) and thereby, lifting the amperage restrictions.
How to Connect Extra Fans to the Motherboard?
Expounding on the explanation prior, you would need either:
1. PWN Splitter
You need a PWM splitter to allow for multiple fans to connect and be powered off of the fan headers in the motherboard, which is usually limited to 1A per header but can vary from one motherboard to another. The motherboard’s spec sheet/manual should contain this information.
The number of fans that can be connected via a splitter is contingent on the amperage of the fans. The setup is very straight forward. The splitter’s female end goes into the header. The male ends of the splitter are where the fans get connected to.
Splitter prices vary on the Y splitter configuration (2-way, 3-way and so on). Needless to say, the pricing scales with the number of ends.
Be very careful not to go over 1A since this could, literally, fry your motherboard. Fans usually have their amperage indicated within the packaging and the manual. If it’s a common model from an established brand and, you should be able to find the specs online.
A proceeding section is dedicated to the amperage discussion and computation.
2. PC Fan Hub
You also need a PC fan hub that also allows for multiple fans to be connected but without the amperage limitations. This is possible since it does not draw power from the headers but, directly, from the PSU via a 15-pin SATA power cable.
With the power SATA power cable connected to the hub, the female end of the hub should be slotted into the motherboard’s fan header. The fans go into the hub’s ports.
Of course, the PC fan hub comes with a higher price tag. An 8-port PC fan hub usually retails anywhere between $15 to $30 depending on the number of ports and features.
More expensive offerings come with baked-in RGB controller, which RGB enthusiasts may actually consider.
How Many Fans Can My Motherboard Support?
A short and safe answer without knowledge of the fans you’re planning to install would be four fans. Understand that overloading a fan header with a current draw more than it can handle will most likely lead to a disaster.
Assuming that your motherboard has three system fan headers, which is a common configuration among standard motherboards for the commercial market, one of them should be dedicated to the CPU fan. This leaves you with two extra system fan headers; meant for intake and exhaust.
If you’re just planning to use a PWM splitter with no direct power input from the PSU and no idea of the current draw of your fans, you need to err on the side of caution and attach only two fans per splitter. Two fans per header on two available headers bring up a total of four fans.
If you’re sure of your fans’ current draw then you just need to make sure that the total for every fan connected to a single header via a PWM splitter does not exceed the maximum amperage rating of each header as per the motherboard’s specifications.
Most motherboards allow for a 1A current draw for each fan header. However, it is of utmost importance for you to confirm this before trying out your planned fan configuration.
If you have a CPU fan hub that can connect and draw power directly from the PSU then you’re free of your fan headers’ amperage restrictions. The average CPU fan hub allows for at least 8 fans to be connected, which should be more than enough for your cooling needs.
Computing for Amperage/Current Draw
Most fans will have their amperage/current draw indicated somewhere; be it the packing, stickers on the fan itself or the manual. However, in case you can’t find any mention of the amperage in any of the aforementioned places, you can still derive it provided that you are aware of the fan’s voltage and wattage.
The formula is quite simple: A = (Watts/Volts). Take for instance the Noctua NF-A14, which is a 1.56-watt, 12-volt fan. Given the formula, we can calculate that its current draw is 0.13A.
This answer matches that of what is listed in fan’s technical specifications.
Fan Sizes in Relation to RPM and Current Draw
While a bit overlooked, another key factor on how many chassis fans you should have is each fan’s dimensions. Most computer cases these days will cater to either 120-mm or 140-mm fans depending on their width. Smaller, thinner cases usually call for 120-mm (120 x 25 mm) fans as they cannot cater to 140-mm (140 x 25 mm) fans.
Note that as a rule of thumb, bigger fans mean lower revolutions per minute (RPM) as they require less to move as much air as the smaller ones.
Continuing on with the above-cited example, the Noctua NF-A14 clocks a maximum of 1500-RPM. Its smaller brother, the Noctua NF-A12x25 FLX, which is 120-mm, has a maximum RPM of 2000.
However, do not mistake the size of the fans to be directly proportional to the current draw and the wattage. Both are rated at 12V but the bigger Noctua NF-A14 actually has less current draw at 0.13A while the smaller Noctua NF-A12x25 FLX draws 0.14A.
This is why it is important to know exactly how much current each fan draws.
Other Factors to Consider when Choosing Fans
If you’ve got the technical side of things sorted out already, then you’re free to move on to the finer details of the fans; namely the noise levels, color scheme and RGB. And while value for money should also be considered, most fans stay within the same price range (sub-30 USD).
The noise levels are quite important, especially if the pc is meant for daily use. The constant humming, at escalated noise levels, can be bothersome.
There are quiet fans out there. A good example would be the ones cited above. The NF-A14’s maximum dBA is 24.6 while the NF-A12 is at 22.6 dBA, which are quietly excellent.
Another factor to consider is the color scheme. While functionality is what’s most important when building a PC, matching the fans’ colors to that of the motherboard/RAM or other installed components isn’t a bad idea.
And while we’re on aesthetics, RGB fans are quite popular nowadays. If you like this trend then you might as well consider getting RGB fans. However, be prepared to pay more for these RGB-equipped ones.
Moreover, to squeeze the most out of these RGB fans, you may want to get a PC fan hub that comes with an RGB controller. The lighting effects, especially if customizable, can give another dimension to your workspace.
Also Read: How to Get Ants Out of a Laptop?
How to Install Case Fans
This article on how to connect extra fans to the motherboard sheds light on the complexities of adding more fans to a system unit. While installing more fans can seem to be very straightforward, it does carry a certain amount of risk.
Hopefully, the cautions and warnings emphasized within this write-up gets taken seriously. A dead/fried motherboard isn’t any fun.