Detailed Tutorial: How to power PC fans with a computer power supply.

Fairly basic, but perhaps useful. Enjoy.



So you're trying to keep your grow box cool and picked up a couple of computer fans, and you also have a computer power supply. At first consideration, this may seem rather straight forward – just plug them in and go, right?

Unfortunately the problem your likely to run into is the realization that there is no way to turn on the power supply when it isn’t attached to a computer (specifically, to a computer motherboard). The motherboard controls the PSU and it is designed to be started via the motherboard on modern computers.


How-to:
1. Locate a power supply. An old computer or a second hand computer store are good places to look. This unit is conveniently rated at 420w max (don’t worry, it doesn’t use this much power with only fans connected. Typical fans use about 2 watts each).




2. Make sure the power supply is unplugged. Safety comes first.
Find the 20 pin connector. It is the largest connector coming out of the power supply.




3. Locate the green wire on this connector. Attach it to the black wire beside it as illustrated in the following picture. You can use a small piece of wire, a paper clip, or simply cut the two wires in question, strip the ends, and twist them together. Be sure to use electrical tape or similar to avoid a short.




4. You’re done! Yeah, that’s it. Plug in the power supply and it will turn on.



Troubleshooting:

If the power supply doesn’t turn on, make sure the I/O button on the back of the power supply is in the on position. Also make sure that the voltage is set to 110V if your power supply has a 110-220V switch on it.
Also note that the green and black wire must remain connected even after the power supply starts up.



How to connect a fan(s):

If your fan came standard with a 4 pin connector, simply attach it to one of the 4 pin connectors on the power supply. Most are double ended so that you can connect several fans.


If your fan doesn’t have a connector, or uses a 2 pin connector, cut it off and connect the red fan wire to a yellow 4 pin connector, and the black fan wire to the black 4 pin connector wire beside it (see image below).



If your going to hook up multiple fans this way, just connect the other ones the same way to other available 4 pin sockets, or all to the same one in parallel if there aren’t enough (ie: if you have 3 fans, connect the red wire of all 3 of your fans to the same yellow wire, and all 3 of your fans black wires to the same black wire).
Do not connect in series as the fans will run at a reduced speed or not at all.
Good luck!

Cool. Knew there was a way to do it just didn't know which wires were needed to hot-wire it.

Cool stuff Lemon, just what I neded. You just solved my problem. Tnx a lot.

Man i have been look for a way to do this.....Thank you very much

No problemo. Any questions, just ask!

nice. I run my lcd monitor off of a power supply. Now I can use it with my laptop too. your the man.

do you happen to know what wires you would need to be crossed on an old at power supply?

i always hated throwing those things away . i figured there had to be a use for them . nice work !

Thank you so much--I have been wondering how to do this for awhile!

Great post!

Definitely Thanks!

Definitely Thanks!

Afte setting up my cab, lining it with Mylar, and putting up the T5's, I stuck my thermometer/hygrometer in over-night. Next morning, it was 85'F,20% rh!! Knew I needed to get the temp down, humidity up before planting and your info. will be the ticket to do so. Thanks again!

Little bump up, Lemon; this is a good diy'r for people. It's definitely a winner.

Just what i have been looking for great job! just one question though, what to do with all the other wires?can they just be cut off and taped up?

Is there any way to run a power strip off of the power supply? Im going to have 2 fans, and wanted to only have the one power cable running out of it so that my PC looks a bit more realistic.

very cool ..i like to run mine off cell phone chargers but this is excelent!!!!!!!! if you need them to pull full power..a small scrubber perhaps..

Growler said:

Is there any way to run a power strip off of the power supply? Im going to have 2 fans, and wanted to only have the one power cable running out of it so that my PC looks a bit more realistic.

Click to expand...

http://www.icmag.com/ic/showthread.php?t=70544

This should be something that would help u out. I just hooked it up for my PC case and it really saves alot of space. make sure to read the edit about soldering it on before u heat shrink or caulk.

Great thread, for some reason my PS has what I think maybe an 'auto-shutoff' feature?

it seems to be random. sometimes shuts off after 20 minutes of being on, sometimes after 20 hours..

the green and black are connected. I had found 2 pins that when connected and disconnected immediately, restart the fan and PSU.. but has anyone had this problem and/or found a permanent solution to keeping the PSU always on?

Your power supply may be a dud. Try another.

Not my pix but i have this setup with a fan speed controller. 2 120's moving 69.15CFM at 18dB ea inline cooling a 400w HPS cooltube. straight line in one side of the cab and out the other. Also intake & exhaust scrubbed!!! Guess where the activated carbon goes. The power supply has no fan & i run a digi ballast. Stealth mon

man, i feel stupid. all these posts of people with success and here's me wallowing in failure. The power supply fan kicks on so I know the 20-pin connector is shorted properly but the 120mm doesn't budge. The fan's wires aren't color coded (two blacks) so when one didn't work i switch them but neither worked. it seems so simple, why does god hate me?

PC POWER SUPPLY, RUNNING CFL'S ALSO

PC POWER SUPPLY, RUNNING CFL'S ALSO

Thanks for the wiring info, I will use this in my next build but my question is now, is it possible to connect a power strip to the supply so that it also runs fans lights and pumps and have one neat cord coming from the back of the case?

Lemon, thanks so much. I've linked people to this thread so many times. It's finally been very helpful to me as well.

GardenCaress, are you sure that your fan is DC and not AC? Look on the sticker. If it doesn't say, google the serial number and read it's specs.

Ghostwolf read here. And be careful.