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5-pin Fan on a 4-pin Connector?

Eschaton
  • 74 months ago

What am I losing if I do this? I have a great CPU cooler, but the fan cable it has needs 5 holes. Nevertheless, I was able to get it to turn on by plugging it into my mobo's 4-pin CPU fan header, but do I lose speed control or something; I thought that's what the fourth wire in a 4-pin connector was for all along. Is it a temperature read? Thanks in advance if anyone knows the answer; I wasn't able to find it by Googling.

Comments

  • 73 months ago
  • 2 points

I can shed some light on this which is far more reasonable and perhaps more correct.

On the commercial products from HP and I believe Compaq, they used CPU cooling fans and heat sink assemblies which used a 5-pin connector and M/B header.

On HP Workstations within the Z400, Z600 & Z800 series, such as I have, the corresponding HP #463991-001 cooling fan and corresponding M/B pin-out header is 5-pin, in this case for the Xeon Quad core processor.

Although HP actually has errors within all three of the Service & Maintenance Guides regarding pin-outs, the Z800 has it correct within the actual diagram.

If you were to look at the header with the key orientation toward the top, Pin 1 is on the right and Pin 5 is on the left. The pin-outs according to the Z800 S&M Guide designates them as:

Pin 1 = GND; Pin 2 = +12v; Pin 3 = TACH1; Pin 4 = PWM; Pin 5 = TACH2

However, in my case, there a shunt, or black jumper wire, connecting pins 1 & 5 on the back of the connector.

There are some workstation and server fan connections which are also 6-pin, specifically when addressing TACH2 and PWM2 parameters.

I hope this helps!

  • 73 months ago
  • 2 points

Meh, I sold the thing. Not my problem any more!

[comment deleted]
  • 73 months ago
  • 2 points

BTW, your photo looks exactly like my CPU cooler and heat sink assembly.

I'm actually getting three of the Noctua NF-B9 PWM fans and replacing all three in my Z400 to make it even quieter for a home recording studio. I'm going to be using a 5-pin USB IDC M/F connector cable and jumping pins 1 & 5, so that the supposed Tach2 still gets the GND it's getting now (to be on the safe side for the CPU).

  • 50 months ago
  • 2 points

Hi, I realize that this chat happened a while ago but figured I would try my luck anyway :)

I have the z420 and the CPU fan is very loud, thinking of buying Noctua Fan NF-A9 PWM to replace it so I lower the fan noise a little. I have the same problem as you though, the CPU fan connector on the board has 5 pin and the noctua comes with 4 pin. I checked adapters etc but not sure if they will work at all. Your solution seemed interesting, did it work well after all? I would very much appreciate if you could help me out on this, it's rather confusing!

  • 74 months ago
  • 1 point

One more detail: the 5th pin has a black wire that loops over to the 1st pin, which has another black wire leading back up to the fan. Seems to indicate to me that the 5th pin isn't doing anything, per se.

  • 74 months ago
  • 1 point

What cooler are you using? Never seen a 5-pin fan connector.

In any case, it sounds like a second ground connection. Here's the pinout for the 4-pin connector:

http://www.allpinouts.org/index.php/Motherboard_(CPU)_4_Pin_Fan

So if one end is looping around, it's either the ground or the control line - and VERY unlikely for it to have two control pins.

  • 74 months ago
  • 1 point

Thanks phillip! Yes, it's unlikely I'd be able to tell you the exact model of the cooler; it looks to be some sort of Foxconn contraption that was OEM for this z400 workstation I'm working on. When I complete the build I fully intend to do a photo-op of all the weird things that this build has, to include this 5-pin/4-pin setup before I replace it with AIO water cooling.

I agree with the idea that it could be a ground; I was taught that black wire = ground in most cases, anyway.

FWIW, this is exactly what it looks like: http://i.ebayimg.com/00/s/OTU2WDEyODA=/z/g2EAAOxyzi9SglGu/$_57.JPG

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