David Webb

there may be a technical issue of replacing the psu. i think there should be some plugins remained that not going to let your pc on. if your pc is starting a beep sound that you should fix you RAM properly or you can even check you cable. If everything is ok then there's problem in your power supply unit. Confirm the supply current coming in and out if its not working properly then supply is sure dead. Same case happen with me, may be there's a problem in your psu. I suggest you should go the new psu or try to repair it or replace from the tech store where you get it. Look for some of the best 750 psu that can help you along.