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Why do fans have two plugs?

Last response: in Overclocking
July 20, 2012 10:18:57 AM

Most case fans I've seen, including my own, have two ports like this:

In that specific picture, I use the bottom plug to connect it to my PSU. But the top plug is unused, what's its purpose?

More about : fans plugs

July 20, 2012 10:37:06 AM

Hmm, never come across that before, none of my fans have that arrangement. But I suspect it's because fans draw very little power it acts like a splitter so you can connect other peripherals via the top molex without the need for tying up more of your psu available cables.
a b K Overclocking
July 20, 2012 11:55:29 AM

those type of fans are used to connect directly power supply.
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July 20, 2012 12:36:28 PM

xtreme5 said:
those type of fans are used to connect directly power supply.

I know that, but there's two plugs, am I right to believe that the other plug is to be able to connect another fan to it?
July 20, 2012 12:55:11 PM

That's what I suspect it's for, so you can 'daisy chain' them.
July 20, 2012 1:36:39 PM

Yes, since the fans are plugged directly into the PSU you are able to daisy chain other fans, hard drives, other things with molex connectors.
July 20, 2012 4:20:16 PM

Keep in mind though the fans will run at the max speed and you won't be able to adjust the speed through software/bios means because the fan is directly connected to the PSU via molex.
a c 330 K Overclocking
July 20, 2012 9:09:34 PM

Power pass-thru- like other have mentioned, you can run additional molex connections from this.