REQ: 7v 4pin fan guide

[phonicsmonkey]

it was posted a long time ago, i had it faved till i reformated, anyone have the guide? or i think there was just a picture on how to do it.

also would this work on YL 120mm fans? or do they need 12v to start or something.

thanks in advance

 

[Zepper]

7V will start YLs OK. Just put the 5V (red on PSU wires) to the ground (black on the fan) and put the Yel wire +12 from the psu to the red wire from the fan (also +12). make sure the fan's ground is NOT connected anywhere else!!! Not to the 3-pin mobo connector for sure or you'll be shorting out the +5 from the PSU. If you want to monitor the tach speed, this may not work as the output fromt he tach is relative to ground. So if you want to monitor the fan, you will need to put a resistor in the fan's red wire, that way the tach output will be relative to true ground. That would take about a 15 ohm 2W resistor. Or run it off a fan controller.

.bh.

 

[Ayah]

Zepper FTW.

 

[smopoim86]

so that really works, just connect the fan ground to the 5v?

 

[Zepper]

On most machines yes. Places like SVC carry stock power adapter cables just for the purpose. When the PSUs had -5V leads you could get several steps. 5, 7, 10 (-5 on fan ground +5 on fan hot) and 12V (yes, some fans will actually start and run at 5V).. It is the voltage differential between the two leads that the fan will "see".

.bh.

 

[MrDudeMan]

Originally posted by: smopoim86
so that really works, just connect the fan ground to the 5v?

labelling the wires as positive and ground is the cause of your confusion...really it is the direction you want current to go, and you want the side with lower potential on the "ground" wire. you could just as easily put 150V on the "ground" wire and 155V on the "positive" wire, and it would still work and operate as if 5V and 0V were applied.