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How do I power 80mm fans from PSU?

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  • How do I power 80mm fans from PSU?

    I am thinking of building a custom "box" to house my Aopen Mini PC and other components I will be using. What I want to do is install 4 - 80mm x 80mm fans into the box to allow for ventillation and heat dissipation. The idea is good, my only problem is how can I power them? If I were to take a normal PC PSU and just plug it into a power source; will it power the fans (using molex connecters from PSU) or does the PSU have to be connected to a motherboard to power on? If you could help it would be greatly appreciated.

  • #2
    Is this for car use? If that's the case how would you plug in a normal PC PSU?

    To answer your question.. Most 80mm fans require 12V which a PC PSU provides.
    Current Vehicle: 2007 Dodge Nitro

    Second Vehicle: Sold it :( 2005 Dodge Ram 1500 Quad Cab

    First Vehicle: 2003 Ford Ranger

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    • #3
      Yes, This will be for car use.

      I guess that is my other question. Can you power a PC PSU without it being connected to a motherboard? Example: plug into an inverter?

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      • #4
        You could yes.. But why would you want to do this? What are you going to use to power your carputer?
        Current Vehicle: 2007 Dodge Nitro

        Second Vehicle: Sold it :( 2005 Dodge Ram 1500 Quad Cab

        First Vehicle: 2003 Ford Ranger

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        • #5
          I am going to use a Carnetix P1900 to power the Carputer. (just have to figure out how to wire it to the ignition, etc.) The reason I want to do that is to power the 4 Fans that I want to put inside the box to keep the box cool and vetilated.

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          • #6
            Hmmm. The Carnetix I used was strictly for startup / shutdown.. You sure you don't have to plug the carnetix into an actual PSU?
            Current Vehicle: 2007 Dodge Nitro

            Second Vehicle: Sold it :( 2005 Dodge Ram 1500 Quad Cab

            First Vehicle: 2003 Ford Ranger

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            • #7
              Carnetix P1900 is a DC-DC PSU, that also has an on-board Startup/Shutdown controller. As for the fans, you can probably run them to the 12v line that the P1900 offers (probably going to your screen right now).

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              • #8
                Yeah the P1900 supposedly is a 140W PSU and startup/shutdown controller. If I could use the carnetix psu to power the fans any idea on how I would do that? The fans I ordered have 3&4 pin connecters (molex). The other thought on that was I wasn't sure if the Carnetix would have enough Wattage to handle MiniPC and 4 Fans. Any ideas? I don't have any of this hooked up yet, just doing the prep work. Somehow I guess I can power the MiniPC using the Carnetix.. I'm not exactly sure how I will be doing this though.. so any suggestions would help.

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                • #9
                  12v for fans

                  The fans are 12 volts correct?! Why not wire the fans into an ignition output, that way, whenever you turn the key in the "on" position, the fans come on with the rest of the car, or you can either wire them directly to the battery with a switch(fused of course) and control them manually. Just a thought.

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                  • #10
                    That's an idea. I am trying to run as few wires to the battery/ignition as possible though. I am trying to keep it so that the box is pretty self contained under the drivers or passengers seat with minimal amount of wiring. Unless I could some how hook up a distribution block in the "box" that connects to a ground & ignition 12v+ line. If I were to do this where would be the best place to splice into the 12v+ ignition line? Should I use the same line used for the radio? or will that cause a short later on? If I could somehow connect a line from the battery to a distr. block in the "box" that would only receive power when the car is on that would be the best solution. I just figured that a PC PSU would be the quickest/easiest solution?

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                    • #11
                      Why not wire the fans into an ignition output
                      This is exactly what I do in my center-console-mounted system. Works great.
                      MikeH

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                      • #12
                        To answer your original question, you can utilize a PC PSU without a motherboard. On the ATX connector of the PSU, there should be one green wire. Short this wire to ground (connect it to a black wire) and the PSU will power up with its switch. However, you do realize you'd need to plug this PSU into an inverter, right?

                        You still have other options which may be better for you. I just didn't want to leave that one hanging.

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                        • #13
                          Design Plan:

                          Here is the basic picture of what I am trying to do with the box I want to design to house everything.

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                          • #14
                            One idea that you might want to consider is using a simple 12V relay. I think they're like $2.50 at you local auto parts store. ( look here for a diagram http://www.the12volt.com/relays/relays.asp )

                            ***I could be wrong with this but if the fans are just basic 12V in to work then this should work.

                            What you'll want to do is run the power cable from you battery directly into a distribution block. From the distribution block run on power cable to your PSU and run another into the relay (into #87 on the relay). Run a ground wire out of #30 and run an ACC/Ignition wire into #87. you can tap into the radio's Ingnition wire even if it is running to other things. That is a constant 12V source that doesn't fluctuate and won't cause problems (I "daisy-chained" off of my amp to my SDC with no problems). Now run a power wire from the #85 on the relay to one of the fans and wire them in parallel.

                            Basically whenever power is applied to the ignition wire it closes the circuit in the relay to allow 12V power to the fans. Without ignition power (radio isn't on) you have no fans. Also if you are running your PSU off the same ACC line then the two will be on at the same time. Plus this absolves any risk you might encounter from messing with the PSU. If you want to make it all nice and pretty go to RadioShack nad pick up a "project" box to house it all...

                            Hope that helps!

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                            • #15
                              On the diagram, you only have 1 fan shown. I think your cooling would be much better if you had one fan blowing in, and another blowing out on the other side - Creating an air flow through the box. The "exhaust" can be accomplished with simple vents, but a fan would probably increase the flow substantially.

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