Hi. I had a few spare computer parts laying around, so I decided to build a computer in a cardboard box. Everything went fine, and I turned on the PSU. It worked, but then the mobo started beeping so I shut it down. When I tried to turn the PSU back on, it wouldn't start, even the fan wouldn't turn. The mobo is a pentium 2 mobo, and it only had a spot for a 20 pin connector. I was wondering if the 4 pin connector needed to be plugged in or not or if the psu was somehow fried. Thanks for your help.