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44507

September 10th, 2018 11:00

780, CPU fan pin out

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?

9 Legend

 • 

47K Posts

September 11th, 2018 04:00

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

 

19 Posts

September 11th, 2018 05:00

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

34 Posts

October 22nd, 2018 10:00

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?

9 Legend

 • 

47K Posts

October 23rd, 2018 10:00

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

9 Legend

 • 

47K Posts

April 18th, 2022 21:00

@nex86 

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

The other fan error is because Dell fans are 4000 RPM fans that use 24W of power.  Dell fan should be kept and a Y cable used if you want to pass Diags and use additional fans.

Dell #7M0F5-A00
Delta # AFB1212EJ-01

52 Posts

December 9th, 2022 15:00

Thanks speedstep for the valuable info as always, I would pay you instead of Dell if I could. I'm not inclined to purchase new Dell hardware given this kind of practice, setting people up for failure just to make a few bucks.

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