I have a Dell Dimension XPS t500. I believe the power supply has gone bad in the machine. I have a tester and when I plug it up I get no lights at all. I have a replacement PS. Placed it in the machine and there was a very high pitch sounding coming from the PS. Tried to power the machine back on and got nothing. Unhooked this PS and tested it and now it test bad. I feel the mobo is causing this but wanted to get others opinions. There is nothing wrong with the power on the electrical receptacle as other computers have been plugged into the same outlet and they work fine.