The other day my PSU stopped working. I took a PSU from another computer and hooked it up and it worked fine, it just didn't fit inside my case. So I called a friend who had extra PSUs. He brought them down and we hooked them up. None of them seemed to work. When I hooked the PSU that didn't fit into the case back up, this time it didn't work. I looked on line and found a way to test the PSUs to make sure they were working by attaching a 18ga wire into the green and black 20 pin. Then I tested each component separately. The PSU stay on until I got to the ATX12V 4-pin power connector. That's when it shut off. Does this mean the motherboard is now fried? Help me please.