New to computers need help

[Jordan Reynolds]

I am in the process of buying components and my PSU just came in, should the PSU turn on without being in plugged into a system? like if i just plug it into a wall will it power up and the fan spin?

 

[animal]

No, most PSUs require them to be connected to the motherboard to be turned on. I have seen a 24-pin connector/adapter at Micro Center that can be used to simulate the motherboard having been turned on via the front panel switch, but can't remember what 24-pin connectors were wired together to accomplish this.