How to use PSU fan for case cooling

[VMord]

Hello Tomshardware!

I need an extra fan for my case, and i have a perfectly good working power supply with 120mm fan. So i was wondering if there was any way i could use that fan to cool my case.
I have tried to search around the web for a guide/toturial, but i could'nt find anything good, so i was hoping that you could give me some advice

 

[geekintel]

Unless it it's connected by molex or the same as the 3-4 pins on the motherboard, I would just buy proper one. They're really cheap.