I have a 1.3amp 12cm fan I got from a Antec ATX case that can move lots of air but at full power (12v line) its really loud. Because I can't figure out how to rewire it for PWM control I have to run it on 7 volts using the 12v+/5v- > 7v trick. There's 2 other fans running on 12v and the 1.3amp fan is the only one on 7v. I'm just wondering if this is safe since I dont have the money for a new PSU.
More aboutsingle 12cm trick safe
Yes it is safe, one of the few areas in a computer where I will say an adapter is a good option. Many fans come with those adapters for just that "step down" purpose.
I just got a old terminating IDE connector and switched the negative pin to the 5v line and then wired the wires to the power wires of the fan