This is the CPU fan connection in my Optiplex gx240. It's 3-pin black red and white. I know that Dell sometimes uses a weird proprietary fan pinout connection in a lot of their PC's, but wasn't sure if this is one of them or not.
I was going to replace with a standard 3-pin fan and cut/solder onto the Dell clip. I assume that white would likely be RPM and red + / black -.
Dell of this type with latching black 3 pin connector is grounded for third pin as long as fan keeps functioning. Not RPM. If fan stop working, the 3rd pin become ungrounded and signal a error on next reboot.
When I had these board like this, I made custom fans by tying the ground wire looping from ground pin to that error 3rd pin by. Middle pin is 12V.
Cheers,
Great Northern aka Canada.
So basically, I run the middle 'red' wire to my aftermarket fan's positive 12v connection and then run the black to the aftermarket fan's ground. And if I want to preserve the redundancy, I also run the white to the aftermarket fan's ground.
Then I just ignore the RPM lead since Dell doesn't use that.
Correct?
Point is: The Dell 3 pin fans and this particular Dell motherboard with these 3 pin fan connectors type is middle pin is 12V for supplying fan, ground is black for fan power return, and white wire is for no rotation signal, while running that wire is grounded by the *working* fan itself if it was genuine dell fan.
What I modify like you do, with different fans onto these Dell type, jump bit of wire from ground to no spin pin ground to keep that dell motherboard happy.
Keep in mind on keeping meanings straight in future for other fans. The PWM is a signal that comes from a motherboard to control the fan's RPM. Second thing, PWM fans always have rpm signal output from fan to tell motherboard with RPM support how fast fan is spinning.
RPM signal is also true on PC standard 3 wire fans too. Plain fans is simply a supply voltage and a ground which is two wires.
Another type of fans is no rotation error signal comes from fan and to do so to signal motherboard in event fan is not spinning by fan causes that pin to be ungrounded (voltage comes up due to motherboard's design) on the third pin, this is case for Dell 3 pin fans, not anything else.
Cheers,
Great Northern aka Canada.
Excuse my mspaint skills, but this is what you are saying, correct?
Yes that's correct, good on you.
Cheers,
Great Northern aka Canada.
In case anyone finds this thread in the future...I can confirm that this wiring trick works as stated. Thank you to pentiumspeed.
_tk wrote on 2023-02-18, 02:04:In case anyone finds this thread in the future...I can confirm that this wiring trick works as stated. Thank you to pentiumspeed.
Welcome,
Cheers,
Great Northern aka Canada.