Power for my PC fans?

Hi guys. I have decided to build a grow box like the one Jethro gave instructions for. I have a couple PC fans that hook to a PC power supply. I also have a PC power supply. So, when a power supply is in a computer it is plugged to the motherboard. You hit the power switch and the power supply comes on. I won't be using a motherboard, so how do I make the power supply come on? Just plugging it into the wall won't make it come on. I want to hook about three fans up. I probably also have a normal 12 volt DC power adapter around here somewhere, would this work? But then, how would I wire up three or four fans?

Are the small electric fans I could get that would be small enough to mount in my growbox? That would be a much easier route as afr as wires go, and I wouldn't have the power supply hooked up as well.

Thanks for any help

short the green wire to a black wire on the psu to get it to turn on

Google ATX power supply wiring. You can jumper the switch wiring and make it work. Once you splice the wires together you are set. I am using an AT power supply to run 3 fans it works great, AT does not require the motherboard. ATX wiring is designed to run through the switch, AT wiring does not. If you have an even older computer laying around check that one out. I cant remember which wiring to splice together at the moment.

There is an article on this in the DIY section. https://www.rollitup.org/do-yourself/4105-computer-fan-wiring.html

Thanks. I will try the green to black. Now, I am wondering about these 6 inch clip on fans I see, and they use normal electric. i wonder if one of those bringing air in and one out at the top would be plenty of air flow?

I think I will run to walmart in the morning and see if they sell some small clip on fans. I have a couple old metal handles I could attach inside the grow box, and I could clip the fans to them, then cut holes in front of both fans, one blowing out, one in. then, maybe put dryer vent covers on the outside, like on the outside of your home where you dryer vents. I hate the thought of a PC power supply on the floor outside my box. I would really love a couple normal electric fans if i could find them small enough. 4 inch would be even better if I could find them.

By the way, I purchased two 60 gallon boxes, huge. I set four 8 inch pots in the bottom and they fit with room left. Three plants should have plenty of room for spreading out, that's for usre.

Thanks for the help.