Not familiar with e-machines but when you replaced the PS did you change power cords too? When you push the power on button do you hear the fan(s) running? Check the power cord. Just a stab in the dark here, good luck and wecome to GNz, enjoy your time here! Let us know what happens eh

And oh, check the wall plug esp. if it on its own circuit, check the breaker, simpler things have stumped people (I plead the 5th on that one), reset the breaker on your power bar etc.