Hi, i ordered a new evga 400w psu a week ago. It came today and I plugged it in right away. All connections fit in place. I turned the pc on and it was making loud rattling noises of such. So I immediately tried to turn off. The button on the pc wouldn't turn it off and so I switched it off at socket. (Rattling sound was just screws and stuff nothing wrong with psu) I attempted to try again and my pc wouldn't power. I switched to my old psu and it started fine. Not sure what happened.. help plz