Case fans won't work.

JamesBwoii · 12 Aug 2011 at 11:36

I have two 80mm fans installed in my case but had no way to power them since my motherboard only have one fan slot which was already in use.

I then bought a 4 Pin Molex to 3 Pin fan cable. When I plugged it in, it didn't work.

I knew it wasn't the fans since they work when I plug it into the motherboard. I thought it might be the molex from the PSU, but when I used the molex powering my front fan it still didn't work.

I then thought it was a fault with the adapter, so I got a replacement and that didn't work. I then bought another adapter off a different seller on eBay and that still doesn't work. Why is this?

These are the ones I bought :
http://www.ebay.co.uk/itm/160615213769#ht_867wt_905
http://www.ebay.co.uk/itm/Molex-4-P...uting_CablesConnectors_RL&hash=item19c685a40e

Thanks for any help.

Surveyor · 12 Aug 2011 at 11:47

Hi and welcome to the forum.

Did you try the connectors with the yellow and black wires in the first adapter you linked to?

The red and black wired connectors are only 5V and that may be too low to start the fans.

JamesBwoii · 12 Aug 2011 at 11:48

Surveyor said:
Did you try the connectors with the yellow and black wires in the first adapter you linked to?

The red and black wired connectors are onlt 5V and that may be too low to start the fans.

Yeah, I tried all 4 of the connectors and none of them worked.

Rik1254 · 12 Aug 2011 at 11:50

This has probably crossed you mind, but why not buy a cheap fan controller?

JamesBwoii · 12 Aug 2011 at 11:56

Rik1254 said:
This has probably crossed you mind, but why not buy a cheap fan controller?

Honestly, I'd never even heard of them. After a quick Google and eBay search it seems like a good idea. However, I don't really understand, I plug it into the 3 pin fan thing on the motherboard and then what? From what I understand it will only allow me to control/power 1 fan? I need 4 fans powered.

hibernian1875 · 12 Aug 2011 at 12:00

Fan Controller

Something like this would allow you to plug 3 fans in to the Fan Controller and run the other one off the motherboard. The fan controller usually needs a 4pin molex to power it.

JamesBwoii · 12 Aug 2011 at 12:03

hibernian1875 said:
Fan Controller

Something like this would allow you to plug 3 fans in to the Fan Controller and run the other one of the motherboard. The fan controller usually needs a 4pin molex to power it.

I'll consider getting it if I can't get these cables I already have working.

Thanks!

freddie64 · 12 Aug 2011 at 12:29

Surveyor said:
Hi and welcome to the forum.

Did you try the connectors with the yellow and black wires in the first adapter you linked to?

The red and black wired connectors are only 5V and that may be too low to start the fans.

Could be this, some fans need ~ 7V.

What fans are they?

Tealc · 12 Aug 2011 at 12:52

Strange that they wouldn't power up off an adapter of both those types and they power fine off the motherboard. It's highly unlikely three adapters would be faulty.

JamesBwoii · 12 Aug 2011 at 13:30

Tealc said:
Strange that they wouldn't power up off an adapter of both those types and they power fine off the motherboard. It's highly unlikely three adapters would be faulty.

That's what I thought. Is there any other possible reason it could be happening?

freddie64 said:
Could be this, some fans need ~ 7V.

What fans are they?

The fans I am using are Casecom 80mm and it says on them "12v".

Tealc · 12 Aug 2011 at 14:47

JamesBwoii said:
Is there any other possible reason it could be happening?

Fans are normally quite simple things. You apply voltage and current and the motor begins to turn the fan blades. Provided you have current going down the red wire and it's connected to the ground via the black wire the fan should turn.

All we can assume is that the adapters are faulty. Check that the wiring goes from yellow on the Molex to the red wired pin on the connector and that a black goes to the black.

JamesBwoii · 12 Aug 2011 at 14:54

Tealc said:
Fans are normally quite simple things. You apply voltage and current and the motor begins to turn the fan blades. Provided you have current going down the red wire and it's connected to the ground via the black wire the fan should turn.

All we can assume is that the adapters are faulty. Check that the wiring goes from yellow on the Molex to the red wired pin on the connector and that a black goes to the black.

The wiring seems to be correct.

Surveyor · 12 Aug 2011 at 15:22

Perhaps for some strange reason the fans won't work without the RPM sensor wire (the yellow one on the fan) being connected.

JamesBwoii · 12 Aug 2011 at 15:34

Surveyor said:
Perhaps for some strange reason the fans won't work without the RPM sensor wire (the yellow one on the fan) being connected.

That sounds like the only rational explanation besides the adapters being faulty. Any idea what I can do?

Surveyor · 12 Aug 2011 at 15:58

Buy some new fans.

Try and connect the RPM sensor wires to the one coming from the motherboard fan header.

JamesBwoii · 12 Aug 2011 at 18:39

Surveyor said:
Try and connect the RPM sensor wires to the one coming from the motherboard fan header.

What do you mean by this?

Also, could I just disconnect the yellow wire and see what happens since these fans were around 82p

.

Surveyor · 12 Aug 2011 at 19:06

JamesBwoii said:
What do you mean by this?

Also, could I just disconnect the yellow wire and see what happens since these fans were around 82p .

Join the wires to the yellow wire of the fan you have working from the motherboard header.

I don't see what disconnecting the yellow wire will achieve. We're working on the basis that the fans won't work because the yellow wires aren't attached to anything. Disconnecting them leaves you in the same boat.

JamesBwoii · 12 Aug 2011 at 19:14

Surveyor said:
Join the wires to the yellow wire of the fan you have working from the motherboard header.

Sorry, I think I'm being really stupid, but I don't fully understand,

Do you want me to connect the red and black wires from the fan to the adapter and then the yellow wire to the motherboard? If you do I don't see how that's possible.

Thanks!

Tealc · 12 Aug 2011 at 20:02

I've never heard of a fan needing a tach wire to operate. Generally the tach signal is created by a hall sensor that throws a high signal to the tach wire twice per revolution. It should make no difference whether there's something connected to the other end of this lead. I suppose it could be a safety feature of these fans.

Not quite sure how you'd verify this. I wouldn't be sticking wires onto the yellow wire once it's in the case though. Sounds like a job for bench supply to me.

Or just buy some decent fans.

Surveyor · 12 Aug 2011 at 21:15

JamesBwoii said:
Sorry, I think I'm being really stupid, but I don't fully understand,

Do you want me to connect the red and black wires from the fan to the adapter and then the yellow wire to the motherboard? If you do I don't see how that's possible.

Thanks!

I was talking of connecting the yellow wires from the two fans which don't work to the yellow wire of the fan which is currently working from the motherboard.

As Tealc says, and as I said earlier, buy some new fans.