New Hardware, no Boot

[Riptide1994]

I opened up my pc to install in a psu of 550 watts. but when it turned it on, the fans came on with everything but i got no video signal and no BIOS beep. So i bought a new MOBO and a new set of ram. That didnt work so I bought a new cpu and still nothing. Help guys, i have swaped the PSU with my old one, my ram with my old and the cpu with three different ones. Last thing i need is to replace the PSU.

[Kurtiskain]

First things first, just make sure you plugged in the 4 pin or 8 pin PSU connector
It won't boot without it.