I think this is a really easy thing that I should know, but I am a first time building and my parts just came. I wanted to test things out so I plugged in my psu into an ac outlet and pressed the power switch. There is a fan on it and I don't know if it is supposed to turn on right away or if there is a heat sensor. Or maybe the psu wont even turn on until it is plugged into the motherboard. Thanks in advance!
Because of the way it operates, a PSU and it's fan will only be energised when it's main connector is plugged into the motherboard, and the PC power button is pressed. The fan comes on immediately regardless of whether it has an adaptive fan or not, once it's connected up.