Powering case LED fans

[nicholastank2]

So i Getting the components to put my new computer in, but this is my first build on my own (Bought prebuilt before). I bought a new InWIN 301 and am gonna be putting 5 corsair air series SP120 quiet edition fans in it to maximize air flow and light the computer cause tempered glass i am wondering what i need to power all these fans. I have a ASUS prime b350m-a with a ryzen 5 1500x with stock cooler, and a zotac gtx 1050. I will be getting a corsair cx series power supply at about 450watts (haven't decided which one yet). So any help would be awesome

[mariushm]

Fans use 2-3 watts of power. No need to concern yourself about what power supply to use.

 

Regular fan headers on the motherboard will do - each fan header is good for a bit more than 1A of current (1A x 12v = 12w) , so in theory you can connect 2-3 fans to a single fan header without any problems.

[intender]

the regular sp120's i have in my htpc pull 4.8watts at full load, the quiet ones pull around 4 watts.  as long as you are not using splitters to run all your fans off one header you should be ok.  I wouldnt say its a rule however as I was just looking through my box of fans and found a delta screamer 120, it pulls around 40 watts so unless you decide to run some delta screamers there are very few occasions when you need to take the power draw of fans into account.

[nicholastank2]

Okay, i was wondering where the header goes on the motherboard ? How do they all get connected ?

[mariushm]

Open the motherboard manual and see where the fan headers are on the motherboard.

There's one for the cpu cooler (to the right of the socket and to the left of memory slots) and there's one above the first pci express slot to the left of the battery

There may be others but I can't see them at a brief look

 

if there aren't enough headers, you can use splitters or adapters that convert molex/sata connectors to fan headers (but these don't allow you or the motherboard to adjust fan speed) or you can buy a fan controller which will allow you to control fan speed if you want

 

example of splitter cable : https://www.newegg.com/Product/Product.aspx?Item=N82E16812162059&ignorebbr=1&cm_re=fan_splitter-_-12-162-059-_-Product

Other splitters : https://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=-1 8000&IsNodeId=1&Description=fan splitter&bop=And&order=BESTMATCH&page=1

 

 

 

 

 

[nicholastank2]

Sorry if I seem like I don't really know what is going on Every computer that has been built in my house has been built by my Dad. Would a fan controller be still controlled by the Motherboard like a normal fan ?

[mariushm]

Don't worry about it, I love helping people if I see genuine interest.

 

Would a fan controller be still controlled by the Motherboard like a normal fan ?  With the majority of the fan controllers, no.

 

A fan header on the motherboard has 4 pins (contacts). Through the first two, the motherboard sends power to the fan, 12v. The third pin is used by the fan to tell the motherboard how fast it's spinning, and the fourth pin is there so that the motherboard can send a signal to the fan to adjust its speed.

 

The fan tells its speed to the motherboard by sending a pulse of electricity twice with each rotation, think of it like saying a very short "beep" each time the fan spins half a complete rotation. A chip on the motherboard counts those beeps and that's how it knows how fast the fan spins.

 

The adjust speed signal sent by the motherboard is a bit different and a bit harder to explain in a very simplified way... think of it like a series of pulses or "beeps" that repeat every second with a pause between each series. The amount of time the beeps last and the amount of time between beeps tell the fan what speed should use, the motherboard doesn't tell the fan to go at an exact rotation speed, it can't do that. The adjust speed signal is sort of like adjustment between 30% speed and 100% speed, without knowing the maximum rotations per minute the fan can perform.

 

If you have more than one fan connected to one of these headers and the third wire is connected to all fans, each fan will send its own pulses through that third wire and the pulses get mixed together on the wire because the fans won't all complete half a rotation at the same time. So because of this, the motherboard may be confused and think the fan spins at some ridiculous speed like 10 thousand rotations per minute.

To avoid that, most splitters only connect the third wire to one of the fans and the other fans don't report the rotation speed.

 

A fan controller usually only takes power and manages all the fans connected to it independently. They generally don't connect to the motherboard to one of those headers to report the fan speed or to take a "speed adjust" signal from the motherboard. It would be too "restrictive". You're doing that through knobs on the front panel or through software on the computer (if the fan controller has such a feature).

If some fan controller does have this option to connect itself to a fan header, it will usually send the fan speed signal from one of the fans connected to it, and it may accept the "adjust speed" signal from the motherboard and adjust all fans at same time to that speed or not. But I would imagine such fan controllers are kind of rare, because most people buy fan controllers to be able to adjust speed of each fan independently.