New PC not working when i start it up it turns off again

[prohan]

New PC not working, when I start it up it turns off again. So I just built my first PC and I went to start it up, all the fans ran but I got nothing to the screen. Then I found out that I had missed the CPU power cord so I hooked that up and now when I turn it on it turns straight back off. If I unplug the cord it runs but nothing to the screen.

 

[natx808]

you are sure you plugged the cable (usually) marked CPU 12V to the CPU power socket on the mobo? Does mobo have error code or beep? Try unplugging components to minimal required, just 1 ram stick cpu and video card and see if you get anything. try different ram slots if still nothing. what is the mobo and cpu? if new ryzen perhaps you need the bios flash to accept the CPU.

 

[ArchitSahu]

Full system specs? Check for bent CPU pins.