Catjesus :
I'm looking for a CPU that is equivalent to the FX-6300 but cheaper. Also, how crucial is it for a PSU to have a 12 volt rail?
Well, what games do you most want to play? Different CPUs perform better in different games. Although it'd be hard to find a CPU cheaper than the FX-6300 that performs better with no other information, if you play mostly quad-core games for example, it could be easy to cut the price.
Also, it's absolutely essential for a PSU to have a 12v rail. I don't even think they make them without one? The PSU's full specs are very important. More important than RAM, HDD, or other similar parts.