Another way you can power those PC fans is with any old ATX power supply. Just jump the PS_ON pin (green one on the chart) to any ground pin (black COM) and it will be on whenever the powersupply has the switch on the back flipped on. Then you can connect your fan and choose from +5, +7, +12, +17 or +24V to run your fan using the main power connector or any of the molex connectors. The +5 and +12V are easy to get, connect black wire on fan to ground, red wire to +5 or +12V. The +7 and +24V are a bit trickier, it's not that great for the powersupply but it will work for a few fans not drawing much load. It works by using the difference between voltages. Connect black wire on fan to -5, +5 or -12V, and the red wire to +12V (+12V - -5V = +17V) or (+12V - +5V = +7V) or (12V - -12V = +24V). This way you can undervolt your fan slightly at 7V if you need it to spin a bit slower, even more to 5V if you've got a fan way too big for your application and you want it really quiet, or overvolt to 24V if you've got a fan that requires it or don't mind maybe killing a 12V fan to get some more CFM. Here are the pins to jump to force the powersupply to be on without a motherboard's power switch turning it on:
can you post a how to thread on this as I would like to make this filter for my grow of 18*18*24 inches needs to be near silent for mine tho as right next to my head haha gunna be runnin about 150-200w cfls in there on 2 plant plz post how to happy growin PEACE