Is it possible to connect a 4-pin fan header to my psu?

[izzulgamer]

My power supply is the Cooler Master Masterwatt 750w. I heard that it is indeed possible to connect a case fan’s fan header to your psu buyback I’m not sure how to really do it.

Will I have to mod my cable or anything or does my psu have some kind of 4 pin adapter in it?

 

[Paperdoc]

If you want to connect any fan directly to a PSU power source so that it runs full speed all the time, you will need a small adapter. The PSU output most often used for this is a female (with holes) 4-pin Molex connector about 3/4" wide, with four round holes in a straight line. Its wires are Red, Black, Black and Yellow. An adapter like this will do it for a single fan. If you have more than one you want to power this way, add a simple SPLITTER after this to convert the single output to several. Of course, if you do this, your mobo can never tell you the speed of those fans.

https://www.newegg.com/Product/Product.aspx?Item=N82E16812423172&cm_re=molex_to_fan_adapter-_-12-423-172-_-Product

This one gives you a 3-pin fan male output connector to plug your fan into (either 3-pin or 4-pin, it does not matter) plus a second female Molex to function as the "replacement" for the PSU output connector you just "used". Note that it will connect the fan's Black (Ground) lead to a Molex Black, fan's Red (+12 VDC) lead to a Molex YELLOW, and make NO connection from the fan's Yellow lead.

You have a modular PSU with three output sockets marked "5P HDD/SATA" . The cables that come with it include one that can plug into one of those sockets ad provides three female (with holes) 4-pin Molex outputs (plus maybe a smaller one for a floppy drive) BUT they are called "Peripheral" connectors by your PSU manual.

 

[izzulgamer]

So the main reason I needed to connect one of my case fans to my psu was because i had 4 in total and 3 were all connected to the system fan header.

If I connect all 4 to the system header will it be dangerous? Each fan’s amperage is 0.25 so connecting 4 would push my mobo at its limit. (My mobo is ASUS H110M-D)

So would it just be better to connect 2 fans as exhaust by molex and the other 2 fans as intake connected to the system fan header?

 

[Paperdoc]

Ah, now I know what you really want. It would be risky to connect four fans at 0.25 a eacg toi a single header, although the specs say that is tolerable. The safer route would be to use a 4-pin fan HUB. That device draws all power for its fans fromt eh SU so it does NOT risk overloading the mobo fan header that is its source od the PWM control signal. However, it
REQUIRES that your mobo header actually does use PWM Mode to control its fans, AND that you actually have 4-pin fans. The mobo website claims it can be used in either Mode, so you should be able to set it to use PWM Mode. IF all your fans are of the 4-pin variety, then this will work for you. IF, however, you have any 3-pin units among your case ventilation fans, you can do this only with a particular Hub. So, post back here:

Are ALL of your fans 4-pin?

Then I can tell you what to buy and how to install. That would put all of your fans under automatic mobo-based control, but not overload your SYS_FAN header.

 

[izzulgamer]

Yes, I’ve checked and all my fans are 4-pin and are PWM compatible

 

[Paperdoc]

Good, then you can use a standard 4-pin fan Hub. These items can be confusing because some are also labelled as "Splitters" - wrongly, I contend. This is the way I use the terms. A SPLITTER is a simpler device that only connects all of its outputs in parallel to the inputs from the mobo header.This means that all of the power for the fans must come solely from the mobo header which is normally limited to 1.0 A max load. It has ONE cable arm ending in a female connector that plugs into the mobo header, and two or more male output connectors where you can plug in fans. It has no other types of connections. A HUB, on the other hand, has those two types of connectors/cables, plus one of a third type. This latter ends either in a male 4-pin Molex or in a SATA connector, and it plugs into a matching power output connector from the PSU. The HUB gets all of the power for its fans from the PSU in this way. Its cable to the mobo header does not draw any power from there, but it does pick up the PWM signal on Pin #4 and shares that out to all its fans. BOTH devices also return to the mobo header the speed signal from only ONE of its fans, because that's all a header can handle. The speeds of all the other fans on the Splitter or Hub are simply ignored. This has NO impact on speed control, but it does limit the secondary functions - fan failure detection and speed display - to only that one fan.

The confusion comes also because these devices come in several physical appearances. Most Splitters are just collections of wires ending in connectors, but there are some that look like small printed circuit boards with headers on them. Most HUBS are covered boxes with ports open on their sides (one of them marked as the only one that sends back the speed signal), but some look like just collections of arms of wires (similar to many Spltters, but WITH the third arm type) or like printed circuit boards. So physical appearance does not tell you, but the presence or absence of that third arm that must plug into a PSU output connector is the real key.

So, OP, you need a Hub with at least four 4-pin fan output connectors. Here are some examples.

https://www.newegg.com/Product/Product.aspx?Item=N82E16811999309&ignorebbr=1&cm_re=fan_hub-_-11-999-309-_-Product

That's a box style and its power source is a SATA output from the PSU.

https://www.newegg.com/Product/Product.aspx?Item=9SIACJF7730777&cm_re=fan_hub-_-1W7-005X-00042-_-Product

That's a printed circuit board style. Note it does not have a cable to go out to a SATA output from the PSU, but you must plug such a connector into the wide power input on one end of the board.

https://www.newegg.com/Product/Product.aspx?Item=9SIACJF5497319&cm_re=pwm_fan_splitter-_-9SIACJF5497319-_-Product

That's a cables-only design with 5 output connectors, but this particular one get a very negative review for product quality.

With any one of these, you plig the power connector form the Hub into a PSU power output, and the female standard fan connector into the mobo SYS_FAN header. You must ensure that the BIOS configuration of that header is set to use the normal automatic control system and ti use PWM Mode, not DC Mode or Voltage Control Mode. Then you plug all your case fans into the Hub's output ports, ensuring that one of them is into the marked port that sends back the speed signal. In this way all of those fans will receive sufficient power and that all will receive the same control signal and run at approximately the same speeds, automatically adjusted by the mobo according to heat generation by the varying workload.

 

[Paperdoc]

Thanks for Best Solution.