Silencing FN 120RB

LapX · March 20, 2013

Hi,

I need help silencing my case fans (I will by Gelid wings soon but for now I don't have the money) so I thought I could add resistors on the fans but I seen that it isn't really recomended.

I've seen that I could just link the yellow wire and the red wire on my power supply to optain 7V (on a molex connector I think) or the red wire and one of the black wires to optain 5V but I am not sure on how to do that and what risk I am taking.

Here is the link [url=http://www.silentpcreview.com/article6-page1.html]http://www.silentpcreview.com/article6-page1.html[/url=http://www.silentpcreview.com/article6-page1.html]

This is the part that I am not sure to understand:

Caution! There are people, who will say "You can't feed current back into your power-supply" and they are right!

If you plug something between the 12V and 5V lead, you have to be absolutely sure, that no current is fed back into the PSU. Which means, that you need to have other loads on that 5V lead, which suck out more current than you feed to that lead from the 12V lead.

For example: Your fan uses 100mA at 7V. You take 100mA from the 12V lead and feed them into the 5V lead. If you have a different fan (or whatsoever), that sucks out 200mA from the 5V lead and feeds them to ground, you're fine. 100mA are sucked out of the 5V lead, 100mA come from the 12V lead and 200mA go to ground.

Since usual fans only use 1...3W, you are usually perfectly safe with using the 7V trick there. There a lots of devices in typical computers, which draw much more power out. Peltiers or things with power consumptions[/url=http://www.silentpcreview.com/#] running up to dozens of watts, require careful calculation of what goes out of the 5V lead and what's going in there from the 12V lead.

Thanks.