Sunday, April 12, 2015

DIY 4 pins CPU-Fan adapter to 4 pins CPU-Fan + 3 pins Case-Fan

Some Story background

After i saved the old Acer X1700 motherboard from trash by replacing capacitors, i noticed that the passively cooled GPU was overheating... 45-80+°C (idle/full)
It was time to add a case FAN ... - where ? ... There's no place in there!- Doesn't matter, there's place outside the case!
The real issue was the single FAN port on the motherboard, and no SATA/MOLEX port left.


Making the 4 pins to 4+2 pins
Why not 4 to 4+3?

Here is the scheme:

Intel 4 pins to 4 pins + 2 pins (no tachymeter for secondary fan)

  • The female 4 pins part is plugged on the motherboard CPU-Fan port.
  • The Ground (black wire, pin 1), the +12V, the Sense (tachymeter) and the Control (PWM pulses) are wired to the CPU-Fan (4 wires PWM-capable), and
  • the secondary (SYS) Fan only gets Ground and +12V.
  • We have no use monitoring the rpm of that fan, and it may interfere with CPU-Fan control (on my testing AMD motherboard the CPU-Fan didn't work until i removed the sense connection on the secondary Fan.

CPU-FANSYS-Fan
  • GND
  • +12V
  • Sense
  • Control
  • GND
  • +12V
  • not wired
  • none

Making of
What are those colors???

On the first test i had wired the GND to an orange wire, for the final build the color scheme is slightly different:

MotherBoardMain Cable partCPU-FAN wiresSecondary wiresSYS-Fan
  • GND
  • +12V
  • Sense
  • Control
  • Black
  • Yellow
  • Red
  • Blue
  • Black
  • Yellow
  • Green
  • Blue
  • Brown
  • Blue
  • None
  • None
  • GND
  • +12V
  • Not wired (ctrl)
  • None

Looks messy? and it is, but everything was done with what i had under the hand...

Results
IRL

4 pins to 4+2 pins adapter DIY

The Fan used is fixed with plastic ribbons

GPU Temperatures are really lowered:

BeforeAfter
IdleFullIdleFull
45°C80+°C37°C42+°C