Question How to connect 2pin DC 12V fan to motherboard/smps as a secondary fan?

[SanjibComputer]

I have a 2 pin(analog connector female) fan which is 12V DC. My motherboard doesn't have any 2 pin male point (have a 4pin sys_fan point only). Also my smps doesn't have any molex male point (only 4 pin analog connector female).
now what to do? how to connect it as a secondary fan?
my mb = Gigabyte GA B75 M_S

 

[Fanatical Meat]

When you say analog do you mean a connector like this?



If so and you have a new motherboard just buy a new fan. Dealing with the connector doesn’t make sense for the trivial savings vs buying a new fan.

**your power supply likely has an adaptor or cord but going this route will run the fan max speed all the time
***if using this as a cpu fan absolutely spend the extra dollars and get a new proper fan

 

[SanjibComputer]

When you say analog do you mean a connector like this?

View attachment 12793

If so and you have a new motherboard just buy a new fan. Dealing with the connector doesn’t make sense for the trivial savings vs buying a new fan.

**your power supply likely has an adaptor or cord but going this route will run the fan max speed all the time
***if using this as a cpu fan absolutely spend the extra dollars and get a new proper fan

No, by analog I try to say same as my given attachment pin.

 

[SanjibComputer]

This MB same as my MB.
there is only SYS_FAN 4 pin available.

Just want to know if I can attach my current 2 pin fan with it or not? If possible then how?

If not possible then how attach any fan with 3 pin?

And lastly, If I bought a 4pin fan then this Sys_FAn port will be work. Right?

 

[eddman]

Just want to know if I can attach my current 2 pin fan with it or not? If possible then how?

Download the board's user manual. Find out which pin supplies the voltage (12V) and which one is ground (GND), then connect the fan accordingly. The black wire is ground.

If not possible then how attach any fan with 3 pin?

You just attach it. The connector's shape makes it obvious.

And lastly, If I bought a 4pin fan then this Sys_FAn port will be work. Right?

Obviously.

 

[Mantrid-Drone]

I've just had a look at your first picture and what you'll have to do is is replace the two pin plug connector with a three or four one (does not really matter). The existing two pin plug can't be fitted to modern MB pin headers because of the plug orientation mouldings on both. In fact that two pin plug looks unusual - the more common two pin fan plug is usually described as 2 pin Molex Small and is narrower with different mouldings.

The two leads from the fan, black and red, are, as you expect, simply ground (GND) and power (12v) respectively. See attached images.

The problem is that releasing the connectors cleanly from inside the two pin plug housing maybe tricky. Even if you do that there is a possibility the design may mean that it is not compatible with a standard three or four pin plug housing too.

So, if you do not want to get into the joys of fan pin crimping (a decent crimping tool will cost you more than a replacement fan anyway) I would suggest buying a three/four pin fan extension leading, snipping off the two pin fan plug and the extension's female connector and soldering them together. If you have an old fan that is broken or doesn't work for some reason you can recycle the three/four pin connector and wire from that instead.

Use heat shrink or insulating tape to insulate the soldered joints from each other and more heat shrink and even cable braid if you want to make it look pretty.

Just make sure the correct wires go to the correct extension lead wire/plug connector or you'll find the fan does not work and may cause damage to the MB or PSU.

You could use a spare Molex (F) connector instead of a fan extension cable + plug to run such a fan from a spare Molex(M) PSU connection. Again be careful with the orientation of the connections.

However you do it without the third/fourth wire the fan will run at 100% all the time so if you need to adjust the fan's speed you''ll have to add some form of control to the arrangement.








If you use the connector from an old fan or cheap extension cable many of those do not colour ID the wires, they may be just be thin black ribbon cables. So make extra sure that the connections are all properly identified and joined correctly.

 

[Paperdoc]

It is hard to tell whether you could make the fan's 2-pin female connector fit over the first two pins of the mobo 4-pin header. But MAYBE.

On the 4-pin SYS_FAN header of your mobo, there is a plastic finger sticking up beside PIns 1-3, and Pin 4 is beyond the "finger" space. Pin #1 is always Ground, and normally the fan has a BLACK wire for that. Pin #2 is the power supply, and the fan's wire for this is normally RED. You do not need to connect anything from the fan to header Pins 3 or 4. If you cannot make the existing connector fit, then you will need to replace its connector with a spare from a regular 3- or 4-pin fan as suggested above. Just make sure the fan's BLACK wire goes to connector Pin #1 (actually, a hole since this is female), and the RED goes to Pin #2.

HOWEVER, you shuld be aware of a likely limit of your mobo. On it the SYS_FAN header is a 4-pin type. BUT this does NOT guarantee it is using the new 4-pin PWM Mode. In fact, the manual for the mobo suggests this header does NO speed control at all! On p. 16 the labels for his header show +12 VDC on Pin #2, indiating it is constant and not varying as a 3-pin fan header would do. Then it shows Pin #4 as "Reserve", suggesting ot is NOT used for anything. Normally if this were a new 4-pin PWM header, this pin would be labelled as PWM. Then if we look at p. 37 where the configuration of the CPU_FAN and SYS_FAN headers is detailed, there is NO information about options for the SYS_FAN header. It appears you have NO options to set, and that is further indication that the header makes NO attempt to control its fan's speed. No doubt any fan connected there WILL operate, but it is very liekly it will always run full speed.

 

[eddman]

HOWEVER, you shuld be aware of a likely limit of your mobo. On it the SYS_FAN header is a 4-pin type. BUT this does NOT guarantee it is using the new 4-pin PWM Mode. In fact, the manual for the mobo suggests this header does NO speed control at all!

You are looking at the wrong manual. That picture is not of his motherboard. His model does support PWM for the case fan header.

IINM all manuals say +12V, so you cannot tell from that if the voltage can be altered or not. You can tell from the bios settings though, and as you stated, that model doesn't support it.

 

[Paperdoc]

eddman, you are right, of course. I did not catch the mobo spec in the first post and used the photo (wrong mobo). In fact, the GA B75MS board manual on p. 11 shows labels for BOTH fan headers indicating it uses only the newer PWM mode. Further, the configuration info on p. 19 also indicates the same. (By the way, in my post regarding the wrong mobo, I was using the 12 V label and the "Reserve" label plus the lack of configuration options to conclude it does no control.)

OP, this changes the details, but not the result, unfortunately. When you try to connect a 2-pin fan to that header, the ONLY way to control its speed is by using the older Voltage Control Mode (suited to 3-pin fans), in which tie viltage on Pin #2 is varied. Your mobo says it keeps that voltage at a constant 12 VDC, the standard way for a PWM Mode header. So it will only run your fan full speed all the time.

 

[Mantrid-Drone]

......which is what I said too.