it is a new one, however, during this process, I've been trying to get the old one to work too. and now both are doing the same thing (I turn it on, the fan on both the CPU and the power supply and after a couple of seconds, both fans shut off.)

Also, i tried building the computer outside the case, and it still does the same thing. However, if I do it that way, does it matter that the power switch isn't hooked up?