# Powering a 12v fan via 5v USB



## Toothless (Feb 21, 2015)

Basically what the title says, but will there be any issues besides the fan spinning slowly?


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## Brusfantomet (Feb 21, 2015)

All the fans that will spin will be slower than at 12 V, and some will not even start.

To get the fans to work as if they were on 12V you will need a boost converter from 5V to 12V  Like this one 

This one has a USB connection on it


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## Toothless (Feb 21, 2015)

I may have to get one of those later down the road, as my main concern is if the fan will burn out the USB port or not.


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## m4gicfour (Feb 21, 2015)

No, as long as you connect it properly, you'll be fine.

Check the amperage rating on your fan. Most will be ~0.25A or similar. This is at 12V, so at 5V it'll be using less than half that. USB2 can supply up to .5A to each device. USB3 can supply more. (in reality, the physical ports and supply can usually provide much more, but this is what the specification allows).

Your main problem is going to be that a LOT of fans won't start at 5V


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## Toothless (Feb 21, 2015)

I do have a USB hub that can plug into the wall, if that helps.


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## AsRock (Feb 21, 2015)

Well a hub is generally cheaper than replacing a motherboard , and as some one else said make sure the ampage is low on the fan so no PANA fans and such.


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## Toothless (Feb 22, 2015)

It's just 80mm to 120mm case fans being used. Normal stuff.


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## R-T-B (Feb 22, 2015)

Simple volt logic in me asks why you can't use 2 connectors, and join the dc current to make 10V.  Pretty darn close, no?

PS:  If you need case fans Toothless, I can stick some freebie 120MM in your PSU you just bought.  They are old dirty bitcon mining ones  but they still spin.   Coolermaster sleeve bearing models IIRC.


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## Caring1 (Feb 22, 2015)

R-T-B said:


> Simple volt logic in me asks why you can't use 2 connectors, and join the dc current to make 10V.  Pretty darn close, no?
> 
> PS:  If you need case fans Toothless, I can stick some freebie 120MM in your PSU you just bought.  They are old dirty bitcon mining ones  but they still spin.   Coolermaster sleeve bearing models IIRC.


That would still result in 5V, but double the amperage available.


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## R-T-B (Feb 22, 2015)

Caring1 said:


> That would still result in 5V, but double the amperage available.



Not if series wired.

http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel


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## OneMoar (Feb 22, 2015)

wiring usb in series is a good way to burnout the usb port or fry the motherboard


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## Caring1 (Feb 22, 2015)

The O.P. doesn't say what the source is apart from being USB, so I assumed a port on a desktop.


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## m4gicfour (Feb 22, 2015)

R-T-B said:


> Simple volt logic in me asks why you can't use 2 connectors, and join the dc current to make 10V.  Pretty darn close, no?
> 
> PS:  If you need case fans Toothless, I can stick some freebie 120MM in your PSU you just bought.  They are old dirty bitcon mining ones  but they still spin.   Coolermaster sleeve bearing models IIRC.





Caring1 said:


> That would still result in 5V, but double the amperage available.





R-T-B said:


> Not if series wired.
> 
> http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel





OneMoar said:


> wiring usb in series is a good way to burnout the usb port or fry the motherboard





Caring1 said:


> The O.P. doesn't say what the source is apart from being USB, so I assumed a port on a desktop.



No NO *NO* *STOP

Your PSU IS NOT A BATTERY *

You can't series wire PSU connections in a PC. All same-voltage connectors originate at the same place in the PSU. Trying to wire in series is a DEAD SHORT and you will either: 

1) Trip the OCP in the PSU preventing it from turning on
or more likely
2) Fry everything involved and start a fire


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## Caring1 (Feb 22, 2015)

And your reason for quoting my posts in that rant?
Where did I say wiring in series was a good idea?


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## Toothless (Feb 22, 2015)

Uh.. my power source at the moment is a USB port on my netbook that leads to a hub. I'm trying to find my wall connector for the hub because I know it gives more power.

UPDATE I FOUND THE WALL THING.

Input 120v AC 60hz
Output 5v DC 1000mA


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## m4gicfour (Feb 22, 2015)

Power, yes. Voltage, no. You're making more current available. You (probably) already have enough, what you need is more voltage.

Why not pick up a 12V DC wall wart (do check that it is 12v, DC, and check the polarity of the connector) and use that? They're just as ubiquitous as USB ports. Or you could use the boost converter like Brusfantomet suggested if you're dead set on USB.


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## Toothless (Feb 22, 2015)

Well if there was a direct outlet thing to power fans then I'd get that.


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## R-T-B (Feb 22, 2015)

m4gicfour said:


> No NO *NO* *STOP
> 
> Your PSU IS NOT A BATTERY *
> 
> ...




Thanks for the quick correct.  I did note I was applying simple DC logic and not aparently sensible logic, lol.  Glad nothing got burned.

This is a good case in my instance of knowing just enough to be dangerous.  I'll duck out now.


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## m4gicfour (Feb 22, 2015)

R-T-B said:


> Thanks for the quick correct.  I did note I was applying simple DC logic and not aparently sensible logic, lol.  Glad nothing got burned.
> 
> This is a good case in my instance of knowing just enough to be dangerous.  I'll duck out now.



That was why I made it big and red. Wanted to be sure it got noticed.

It's an easy mistake to make if you don't know how the power supply is wired on the inside. No harm, no foul - and you learned something so you'll never make that mistake again and can correct others... a worthwhile addition to the thread.



Toothless said:


> Well if there was a direct outlet thing to power fans then I'd get that.


http://www.amazon.com/dp/B002TJNDU4/?tag=tec06d-20
http://www.amazon.com/dp/B000BSJGL0/?tag=tec06d-20

That would do you for a whole bunch of fans, just get enough 3-pin adapters and add the amp value for each fan. (For example, say you want to use 5 fans each rated at 0.25A, that would be 1.25A - the supply in this case supports 5A aka 5000mA. As long as the total of your fans doesn't exceed that, you're golden)

The only thing you might have to watch out for is that sometimes these power bricks omit one of the two grounding pins in the four pin connector, so you'd have to bridge the center two pins on the fan adapter if the ground you need is missing. Perfectly safe, but be careful not to bridge either two center pins to an outside pin - that's a short circuit.


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## R-T-B (Feb 22, 2015)

Yeah my background is wiring two 1.5V AA batteries together to (barely) power 5V LEDs as a child...  Not what I'd call an identical situation.  You're right, I'll never advise that again! lol


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## m4gicfour (Feb 22, 2015)

When I was a child (around six years old, I think) I tried to wire up a 120V light socket with 22AWG wire. I also created a short circuit there. It was a good thing that the wires I used were so tiny, since they just instantly evaporated all the wire out of the insulation. 

BLUE SMOKE EVERYWHERE.

I've since learned to do my research first  (and had some schooling in electronics as well)


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## R-T-B (Feb 22, 2015)

I did the same thing with a standard AC socket trying to power a DC project.  About 6 or 7 as well.  No blue smoke but that outlet is still blackened to this day.

Thankfully for me, it was a 10AMP 120V circuit so it just tripped really fast.

That was about when I stopped messing with electronic things.  They seem less magical when they blow up.

Back now to NOT blowing things up...


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## Toothless (Feb 22, 2015)

Okay, last question. Would this be okay to use directly to a fan and PSU? It's a Rosewill fan controller where I took off the part that plugs into the board, showing the three pin connector.


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## m4gicfour (Feb 22, 2015)

It should be fine, yes.

Just to be sure, what do you mean when you say "I took off the part that plugs into the board"

Like I said, some of those molex power bricks omit one of the ground pins, usually the one closest to the 12V pin, which you'll be drawing power from. So if you use one of those to power it, and if that's the case that it only has 3 pins in the molex end, you'd just need to connect the two black wires in the center of that molex together on that adapter. If not, and the molex power brick has all four pins, then you don't need to do anything but plug it in.

If you're going to be using things like this that are meant mainly for use inside a PC case, it's not a bad idea to take some electrical tape and cover all the bare connection points once you've got it all hooked up and working, and of course keep it out of reach of pets and small children.


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## Caring1 (Feb 22, 2015)

I have a fan speed controller almost identical to that, it too came originally with two wires on the molex connectors and doesn't need any work or modification for it to work.


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## m4gicfour (Feb 22, 2015)

Not with a desktop PSU, no. He is however using a NETBOOK.

If he uses an external power brick, those tend to only have 3 pins in the molex end. If the missing ground pin is the one on the 12v side....


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## Toothless (Feb 22, 2015)

This @m4gicfour







The fan would be plugged directly into the controller. Not fan > controller > board.
I'm thinking inside the case now.


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## m4gicfour (Feb 22, 2015)

Okay, I see. It looks like that's just a cable to connect your controller to the mobo in order to report RPM, yes?

In that case, you *might* need to leave the cable it came with plugged in depending how it's wired.

From what I can tell from the photo, it looks like it would be fine to plug the fan in directly.


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## Toothless (Feb 22, 2015)

Awesome. I'll give it a try in a few.


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## peche (Feb 23, 2015)

Toothless said:


> Basically what the title says, but will there be any issues besides the fan spinning slowly?


What do you want to do with?
i use old PSU fans and also old 120mm / 80mm/ Fans for making heat blowers for air fresheners, via USB,

i have done tons of USB fans, they not work as fast as 12V ones but they are OK for refreshing the air near your hands at desktop for example, also they look nice
Regards,

Take a look:


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## m00k (Feb 22, 2017)

Brusfantomet said:


> All the fans that will spin will be slower than at 12 V, and some will not even start.
> 
> To get the fans to work as if they were on 12V you will need a boost converter from 5V to 12V  Like this one
> 
> This one has a USB connection on it



Sorry for the thread revival but hoping for some help along the same lines, I want to run two 80mm fans as efficiently and cheaply as possible in my garage.  They will be running constantly 

Will one of those 5v - 12v converters run two off one connection or best to run one for each fan?

Or any other recommendations?

Thanks


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## eidairaman1 (Feb 22, 2017)

m00k said:


> Sorry for the thread revival but hoping for some help along the same lines, I want to run two 80mm fans as efficiently and cheaply as possible in my garage.  They will be running constantly
> 
> Will one of those 5v - 12v converters run two off one connection or best to run one for each fan?
> 
> ...



I don't think you want to overload it, 5v is pretty low.


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## Vario (Feb 22, 2017)

I run a Koolance 120mm fan on a 7 volt AC adapter for the past 2.5 years 24/7 to cool my modem and router.  Works great.


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## Brusfantomet (Feb 22, 2017)

The easiest solution would be to use a mains (230V or 110 V) to 12V converter, since they are dirt cheap

If you want to run it from a USB port, check the fan rating, 1A at 5V is 5W, while its 0,41 A at 12V, factor in some losses in the converter and you are looking at 0,4A at 12V, so if the fans draw less than 0,2 A each it should be fine to use one of those.
If on the other hand you have a Delta rated at several amps then you will need a 230V to 12V thing.


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## m00k (Feb 22, 2017)

I'm not particularly great on specs and power ratings 

But basically if I can get two of these to run 

https://www.ebay.co.uk/itm/152430563634 

https://www.ebay.co.uk/itm/131578409320 

https://www.ebay.co.uk/itm/311253580924 

Would that seem plausible?

I'm happy enuff with soldering connections etc

Just need two USB plugs two step up's and two fans?

That won't cost the earth to run 24/7?


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## Toothless (Feb 22, 2017)

So after a while of working on stuff, I came to this for you @m00k 

Get a phone charger, like an outlet to USB, USB cable and cut the non-USB end off. Get a 3-pin fan splitter and run the two fans off all that. It'll keep the power required and is pretty easy to DIY yourself.


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## Brusfantomet (Feb 22, 2017)

m00k said:


> I'm not particularly great on specs and power ratings
> 
> But basically if I can get two of these to run
> 
> ...



that fan draws 0,14 A at 12V, so using two should be no problem.

But a 230V to 12V adapter in stead of the phone charger and converter is cheaper and can power more than ten of that fan.


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## m00k (Feb 27, 2017)

Brusfantomet said:


> that fan draws 0,14 A at 12V, so using two should be no problem.
> 
> But a 230V to 12V adapter in stead of the phone charger and converter is cheaper and can power more than ten of that fan.



Have you any links to what I would need by chance?


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## Brusfantomet (Feb 27, 2017)

try clicking on the text "230V to 12V", its a link.

you will also need something to cut wires with, something to strip insulation of the wire with and a soldering iron.
Having a multimeter will also be handy, but is not necessary.

Also note that the exact fan you linket to will run at 5V, but slower than it will on 12V


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## m00k (Feb 28, 2017)

Yeah handy enuff with soldering iron side of things just not sure which converter I would need

With what I'm planning it might be as handy to do the USB plug for each fan as they will be on opposite walls and be easier to run wires from the sockets above


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## Potatoking (Feb 28, 2017)

just get 100-250v to 12v adapter
like this one
http://www.ebay.com/itm/AC100-240V-...-Power-Supply-Adapter-Transformer-LED-Strip-/
you can run as many fans as you like.
also you probably have some old stuff from router or something simmilar, i have like 10 of those


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## SnakeDoctor (Feb 28, 2017)

A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0.


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## m00k (Feb 28, 2017)

SnakeDoctor said:


> A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0.



You've lost me I'm afraid... sorry


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## Brusfantomet (Feb 28, 2017)

With the 12V adapter you are not using a USB connector at all, you just solder the wires for the fans on the wires for from the adapter.

If you absolutely need to have a connector then a standard 3 pin fan header should do, cheapest solutions i could find in my limited ebay search was this fan splitter remove the female connector (the one its one of) and solder the +12V from the adapter to the yellow wire, and the 0V from the adapter to the black wire, you can now connect and disconnect the fans from the adapter.

Or you could get some of  these, as they also are connectors for fans, but more expensive that what i linked to first.

Also, when SnakeDoctor talks about "unit load" fro USB its about what amount of current the USB standard allows for, 500 mA for USB 2 and 750 mA for USB 3 (both at five unit loads). All modern phone chargers supply 1 A, that is why your phone might charge slower if tis plugged into a computer than a normal wall cadger. BUT this has nothing to do with powering some fans from a wall socket.


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## SnakeDoctor (Feb 28, 2017)

m00k said:


> You've lost me I'm afraid... sorry



USB2 support 0.5amps(5 x 100ma devices) and USB3 0.9amps so max draw can be calculated

Op you could use a USB powered hub aswell then separate from laptop power


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## valdotdev (Apr 25, 2017)

Hi there! Sorry for reviving an old thread.

I'm building a cabinet for my video game consoles and I was researching for a way to power two (2) 120mm fans via my PS3 and/or PS4's USB ports. Basically an 1 for exhaust and 1 for intake. I use this fan since I have a few of these lying around.
http://www.coolermaster.com/cooling/case-fan/sickleflow-x-red-led/

What I want is when I turn-on my console, the fans also turns on so they're only active when needed. My problem is that USBs typically outputs 5 volts and 120mm fans are usually rated at 12 volts. Specifically, my fans are rated 12V and 0.35A. Plan B is I'll just use a 12V adapter but I don't want to go that route just yet.

I also have a lot of spare USB cables lying around so I was planning to strip off one end and solder them to the fan, or specifically, the 4 pin molex adapter that comes with the fans so I don't have to strip the cables attached to the fan itself.

So before I do this I would really like some advise if this set-up is doable or if it will actually work. Actually I already tried doing it using a standard 5V smartphone USB wall charger. To be expected, after soldering cables and connecting it to an outlet (220V) the fan is pretty slow but works.

Any ideas/suggestions? Should I use step-up boosters or something? Many thanks!


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## Toothless (Apr 25, 2017)

Use fans that require lower power to run and use the USB charger. I think I've used fans that need lower amperage and those worked better than most other fans.

Your consoles should be able to power them but I'd recommend a USB 3.0 powered hub that has switches if possible for better control. More power too.


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## AsRock (Apr 25, 2017)

USB hubs work a treat, although i am currently checking out thermal controlled ones on a Adapter.

Here's the kind of thing i am on about 
http://www.ebay.com/itm/172468332549?_trksid=p2060353.m2763.l2649&ssPageName=STRK:MEBIDX:IT


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## Brusfantomet (Apr 25, 2017)

i would use a 12V adapter with a 5 volt relay, found  this, a relay that needs 5V to activate, use the 5V from the USB port to activate the relay. This couplets the circuit with a 12V adapter and fans, this is probably the cheapest solution,  but it requires some soldering on your end.


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## valdotdev (Apr 26, 2017)

Toothless said:


> Use fans that require lower power to run and use the USB charger. I think I've used fans that need lower amperage and those worked better than most other fans.
> 
> Your consoles should be able to power them but I'd recommend a USB 3.0 powered hub that has switches if possible for better control. More power too.



I don't want to purchase additional fans as much as possible since I have a bunch of them here. I think 12V 80mm fans runs well on a 5V source but the cabinet already has holes for 120mm fans 

Should the hub have an external plug/psu or a USB 3 powered hub is enough? I imagine the USB 3.0 hub won't do much if you plug it in a USB 2.0 port like with the PS3. Though the PS4 has USB 3.0



AsRock said:


> USB hubs work a treat, although i am currently checking out thermal controlled ones on a Adapter.
> 
> Here's the kind of thing i am on about
> http://www.ebay.com/itm/172468332549?_trksid=p2060353.m2763.l2649&ssPageName=STRK:MEBIDX:IT



I was initially thinking of doing this too. But the limitation of a 5V source is preventing me from trying this out.



Brusfantomet said:


> i would use a 12V adapter with a 5 volt relay, found  this, a relay that needs 5V to activate, use the 5V from the USB port to activate the relay. This couplets the circuit with a 12V adapter and fans, this is probably the cheapest solution,  but it requires some soldering on your end.



I was actually thinking something along those lines if I happen to use a 12V adapter. I was looking for a way to activate the adapter automatically when the console was turned on so I won't rely on a wall plug as a source. Unfortunately, aside from soldering, my knowledge in electronics is very limited so I'm not sure if I can do this, at least not properly. Do you have any resources/tutorials or anything I could use? I even forgot how to make simple circuit diagrams  but I at least know the terminologies.


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## Brusfantomet (Apr 26, 2017)

valdotdev said:


> I don't want to purchase additional fans as much as possible since I have a bunch of them here. I think 12V 80mm fans runs well on a 5V source but the cabinet already has holes for 120mm fans
> 
> Should the hub have an external plug/psu or a USB 3 powered hub is enough? I imagine the USB 3.0 hub won't do much if you plug it in a USB 2.0 port like with the PS3. Though the PS4 has USB 3.0
> 
> ...



connecting a USB 3 hub to a USB 2 port will not magicaly give you more amperes, as you say.
USB 2 specifies 0.5 A, but modern phones usually draw 1A.
USB 3 is spesified to 0.75 A.

if the USB hub gets the power from the wall it will give you more power, otherwise its useless.

for the relay method i can make you a simple working drawing:






this will work IF the 5V from the USB only is powered when the console is active, but the same is true if you power the fans directly from the USB port


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## valdotdev (Apr 26, 2017)

Brusfantomet said:


> for the relay method i can make you a simple working drawing:
> 
> 
> 
> ...



Awesome thanks for the drawing! Pretty east to understand. I'll try it out once I get the parts. Do you have any suggestions for what type/kind of 12V adapter I should get?


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## Brusfantomet (Apr 27, 2017)

Depends on the number of fans you want to use. the fans you linked used 0.35A at 12V, so a 1A adapter will be sufficient for 2 fans, while a 2A adapter will be able to power 5 fans (5 x 0.35 = 1,75).

I would actualy check if you already have a 12V 1A supply already, its a common voltage for older routers and stuff, and would save you a few dollars if you already have it at home.


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## valdotdev (Apr 27, 2017)

Brusfantomet said:


> I would actualy check if you already have a 12V 1A supply already, its a common voltage for older routers and stuff, and would save you a few dollars if you already have it at home.



Yeah I actually have a ton of 'em at home. Thanks a bunch guys!


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## Brusfantomet (Apr 27, 2017)

nice, one less thing to order from ebay then.


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