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2 Iron

780, CPU fan pin out

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Anyone knows the purpose of five CPU fan pins? I need to connect a non-Dell fan which has four wires. Is there 12 V, ground, RPM and PWM as usual or there is some proprietary fan control in place?

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8 Xenon

Re: Optiplex 780 CPU fan pinout

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Dell sometimes swaps the wires around so that you will fry a dell fan on standard and the other way round.

It has 5 pins but only 4 wires are used.

Dell does not publish this. And some dells use standard wiring.

I believe this is correct.

YMMV

 

4pin PWM on 3 pin4pin PWM on 3 pin

 

Dell MB
Pin Number

Function

Dell wire color

Std Fan
Pin Number

Std Fan wire color

Description

1

Sens (TACH)

White/Yellow

3

Green

Sens (TACH)

2

+12v

Red

2

Yellow

+12v

3

Gnd

Black

1

Black

Gnd

4

PWM

Blue

4

Blue

PWM

5

Key

unused

 

 

  

 

 

DELL FAN WIRES AND COLORSDELL FAN WIRES AND COLORS

 


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4 Replies
Highlighted
8 Xenon

Re: Optiplex 780 CPU fan pinout

Jump to solution

Dell sometimes swaps the wires around so that you will fry a dell fan on standard and the other way round.

It has 5 pins but only 4 wires are used.

Dell does not publish this. And some dells use standard wiring.

I believe this is correct.

YMMV

 

4pin PWM on 3 pin4pin PWM on 3 pin

 

Dell MB
Pin Number

Function

Dell wire color

Std Fan
Pin Number

Std Fan wire color

Description

1

Sens (TACH)

White/Yellow

3

Green

Sens (TACH)

2

+12v

Red

2

Yellow

+12v

3

Gnd

Black

1

Black

Gnd

4

PWM

Blue

4

Blue

PWM

5

Key

unused

 

 

  

 

 

DELL FAN WIRES AND COLORSDELL FAN WIRES AND COLORS

 


Report Unresolved Customer Service Issues
here

I do not work for Dell. I too am a user.

The forum is primarily user to user, with Dell employees moderating
Contact USA Technical Support






Get Support on Twitter @DellCaresPro

View solution in original post

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2 Iron

Re: Optiplex 780 CPU fan pinout

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Thank you! I can't say I wasn't searching, but you saved my day. 🙂

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2 Bronze

Re: Optiplex 780 CPU fan pinout

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I have an adapter thats exactly wired like this,
but I'm getting a Fan failure error when trying to use my Noctua PWM fans.
Any solution for this?

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8 Xenon

Re: Optiplex 780 CPU fan pinout

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If you plugged them in wrong you have fried your fan sensors on the fan and perhaps on the board.


Report Unresolved Customer Service Issues
here

I do not work for Dell. I too am a user.

The forum is primarily user to user, with Dell employees moderating
Contact USA Technical Support






Get Support on Twitter @DellCaresPro

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