I know you said you aren't all that knowledgeable...but you probably know more than many G**k Squad employees sadly. The Dynex brand is not known for quality or anything like that. I recommend you move to a nice single-12V rail PSU like the Corsair 650W. You can get them at Newegg.com - Computer Parts, Laptops, Electronics, HDTVs, Digital Cameras and More!
and you don't have to talk to any B**t Buy employees to do it
Don't open the Dynex, it's a little dangerous and could void the warranty, I'm fairly sure a wire is hanging too close to the fan blades inside the PSU.