Sorry, I couldn't resist..........
do you really have to ask that question what with you being a clairvoyant you should just know

Yeah uncle google is your friend. It is easy enough if you know what you're doing to modify the PC supply, but it is in depth and would take far too much to describe it in detail. Not to mention, I haven't done it because I'm afraid of blowing something up, hahaha. I just buy a "meanwell" power supply from ebay, cheap as and works flawlessly.