Computer PSU as power source for fans

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Here's the plan. Making an in-wall 5 shelf A/V rack. I want to get some fans put into each shelf, as to properly ventilate the heat out of the front open only shelving unit. The plan is to put 1 120mm fan per shelf, on the backside of the A/V rack to pull the air through the front, and out the back of the shelving unit.

Instead of buying a bunch of expensive "A/V coolers" from the net, i was going to attach a computer power supply unit to the shelving unit, and have it power my 5-120mm fans. Here comes the safety issues i'm having.

Using a paper-clip to fool the PSU to think that a motherboard is attached is simple...but is it safe? More than likely not. I'm hoping to find a permanent way to make my power supply a "safe" power source for my fan needs.

I'm hoping to find some help on this issue without tearing apart the power supply itself.

Thanks in advance!