How would I go on about turning off/unplugging this fan?Maybe I could get an alternative solution?

[Marko_7]

Hello Tom's Hardware!

Noob here,I've bought a pre-built PC(please don't frown upon me) and the case fan(rear,only one,120mm) I got started to act up.

Turned my PC on today and it just started running normally and then it slowed down and started rattling.

Tried cleaning it,tightening and loosing the fittings but it just keeps on rattling.

The noise is driving me crazy so I want to turn it off completely at least until i replace it.

But speedfan,HWmonitor and neither the BIOS won't recognize it so I'm thinking it's wired directly to the PSU,right?

But its wiring is kinda weird,let me explain.

The 3 wires/cables coming out of it go into a 3 pin connector logically,but the the 3 pin connector isn't connected to anything.

Instead,out of the 3 pin connector come out 2 wires that lead to the bottom of another,bigger connector(4 cylindrical metal pins inside it).

And that connector doesn't go anywhere either,instead out of the back of it come out 4 wires that go into a connector that IS CONNECTED to the CD-ROM,and out of that connector come out 5 wires that go into another,unconnected connector.

5 wires from that into another unconnected connector then 5 wires directly into the PSU.

So to map it out:

FAN-3 PIN CONECTOR(unplugged)-LARGER CONNECTOR(unplugged)-CD-ROM-2 unplugged conectors one after the other-PSU

How would I go about doing this.
Thanks in advance!

 

[Paperdoc]

Your suspicion is right. Through all those connections, the fan is being powered directyl from a fixed 12 VDC supply form the PSU. Your system has no control over it, and in fact cannot show you its running speed because the fan has no connection to your mobo.

The simplest way to turn the fan off will be to find the place closest to the fan where it is plugged into another mating connector. Disconnect it there. But DO get a replacement unit as soon as you can.

To help understand, your fan has a set of wires and connectors that "re-create" the power su0pply connector it "uses". Starting further away from the fan, there is a MALE (with pins) 4-pin Molex connector with 4 wires (Red, 2 Black on Yellow) leading to a FEMALE (with holes) 4-pin Molex. This is the "replacement" power output you can use to plug in some other male connector. From the back of that are TWO wires carrying the 12 VDC and Ground connections for the fan. But along the way those wires go into a smaller FEMALE (with holes) 3-pin fan connector, and another pair spliced in there actually carries power to the fan. The concept is that you can plug this fan EITHER into a mobo 3-pin male header (using the smaller connector) OR into a Molex power output from the PSU, but the wiring also ensures that the Molex you "use" for that is replaced by another female Molex.

 

[Marko_7]

Here are some pictures I've taken to make it easier for everyone.

The fan,and the cable that goes out of it.
http://prntscr.com/i68jpt

The 3 pin connector,little bit blurry
http://prntscr.com/i68k3a

The unplugged,larger connector(the connector that has wires coming into the bottom of it,from the 3 pin one)
http://prntscr.com/i68k6q

The connector that goes into the CD-ROM
http://prntscr.com/i68kjg

The first unplugged connector after the CD-ROM one
http://prntscr.com/i68ksi

The second unplugged connector after the CD-ROM one
http://prntscr.com/i68l16

The bundle of cables that goes into the PSU
http://prntscr.com/i68l43

 

[Paperdoc]

The photos help. In fact, the way this provides the "replacement" female connector is the most common way.

In the 2nd and 3rd photos, the wider Molex connector that has two small wires coming out of it towards the fan is really a double connector in one piece. One end is male (with pins) and plugs into a female connector coming from the DVD player. The other end of that same connector has the female holes in it, for use in plugging in another male Molex to feed power to something else. So that one module has both male and female ends to feed power through itself, and then a pair of smaller wires coming out the side to provide 12 VDC and Ground to the fan. You will note that, at the back of the smaller female 3-pin fan connector, those two wires are spliced (inside the connector body) to wires from Pins 1 and 2. Pin 3 on this connector is the one that would carry the fan's speed signal back to the mobo header IF it were plugged in there, so it is NOT connected to anything from the PSU.

 

[Marko_7]

Thanks for the help @Paperdoc,took me a little bit but I figured everything out.
Been trying to connect my 3 pin connector to the 4 pin socket my MOBO has but I can only connect it to the first 3 pins(in other words i can't fit it in the last,4th pin)where my MOBO still doesn't recognize it.

When I buy another case fan I'll experiment with it.

Does every case fan have both the pin connector and the other molex connector or should I ask specifically for one that has both?

 

[Paperdoc]

First, thanks for Best Solution.

Mechanically and electrically, the two fan systems have been designed for the best compatibility they can achieve, although it cannot be perfect. Among other things this means you CAN plug any 3-pin OR 4-pin fan connector into any 3-pin OR 4-pin mobo fan header, and they will work - sort of. Obviously if you match male and female connectors, they each will perform all things they are supposed to. The partial performance things come when you mis-match.

If you plug a 4-pin fan into a 3-pin header it WILL be under mobo control for speed. It's just that the method of control used by 3-pin headers, called Voltage Control Mode or DC Mode, is not quite as good technically as the newer PWM Mode; however, the difference is small and does not matter for most things. If you plug a 3-pin fan into a 4-pin header, as you have found, the connectors only mate for the first 3 pins, leaving the 4th pin open. That is OK. But in terms of performance, this means that the 3-pin fan does not receive the PWM signal from Pin #4; however, since it lacks the new special internal chip that uses this signal, that does not matter at all. What DOES matter, however, is that the fan receives a constant +12 VDC from Pin #2 in this case, so it always runs full speed and its speed can NOT be controlled by the mobo header. In fact, OP, that is exactly the performance you have been getting all along with that fan connected to the PSU directly.

I won't go into full detail here, but most modern mobos are using only 4-pin fan headers. BUT many of them do not use those as true 4-pin control systems with the PWM Mode. You cannot tell from the header pin count what method it uses, and there are about four possibilities of how the headers work. Discerning the truth takes careful reading of the mobo manual.

Post back here exactly what maker and model number is your mobo? Also list what fans you have plugged into which of its fan headers already, and whether any headers are unused. What size is the rear fan that has become noisy? Sizes are the length of the side of the square fan case, usually 80, 90, 120, or 140 mm.

With that info I can advise what type of fan you should search for. Most fans are NOT like the one you have with two different types of connectors, but that type certainly is available. By the way, you must never plug that fan into BOTH a 3-pin (or 4-pin) mobo header AND the PSU connections.

 

[Marko_7]

First, thanks for Best Solution.

Post back here exactly what maker and model number is your mobo? Also list what fans you have plugged into which of its fan headers already, and whether any headers are unused. What size is the rear fan that has become noisy? Sizes are the length of the side of the square fan case, usually 80, 90, 120, or 140 mm.

With that info I can advise what type of fan you should search for. Most fans are NOT like the one you have with two different types of connectors, but that type certainly is available. By the way, you must never plug that fan into BOTH a 3-pin (or 4-pin) mobo header AND the PSU connections.

The mobo model:ASROCK H81M-VG4

It's a 120mm,I forgot the brand since i removed the sticker.But i know it was a decent brand.
Not realy corsair or noctua decent but decent,could've been asus perhaps.

The cpu fan is plugged into the cpu_fan1 slot.

Also I've got 2 gpu fans on my RX470.

I've got 2 unused 4pin male slots next to cha_fan1
An upper and a lower one,the upper one has a wider foundation on which the pins sit on than the lower one,and between them there's a like a wall that's as lengthy as the first 3 pins of the 4 pin slots go.

Here are 2 pictures of that since it looks odd:

The 2 slots
http://prntscr.com/i6m7tj

The ''wall'' that seperates them
http://prntscr.com/i6m89c

 

[Paperdoc]

First of all, are you SURE about the mobo model info? When I look at its manual here

http://asrock.pc.cdn.bitgravity.com/Manual/H81M-VG4.pdf

the diagram of the mobo on p. 11 does not match the photos you have provided. So before relying on that manual for info, I'd like you to check it.

Now, in the photos, what I see (I believe) is the upper connector IS a standard 4-pin fan male header, but the thing below it does not appear to be the same thing. I would not try to use it for a fan until we clarify it further.

The little "wall" you point out is part of the fan header. That tongue (I call it) is placed by Pins 1-3, and Pin #4 is the one beyond the tongue. If you look closely at the smaller 3-pin female connector on your fan, you will see small ridges on one side. When you plug that into the header, the tongue fits between the ridges, and assures that you can only plug it in one way - in your case with the 3-pin connector, leaving Pin #4 unused.