PC wont turn on after installing a new power supply

[Specksan]

The title says pretty much everything. Just recently I got the Corsair RM550x power supply and after plugging in all the cables, turning the power supply on and pressing the boot up button nothing happens. The pc makes sort of a shuffling sound for a really really short time and then nothing happens. The lights on my motherboard lightup and the gpu light lights up but my pc just wont start. My PC was working with my old PSU but I upgraded because my GPU needed a better one. Pls help me.

Mobo: Asus M5A97 LE R2.0
PSU: Corsair RM550x 550W 80+ Gold

 

[TMTOWTSAC]

Is your EPS (CPU) connector to the mobo for plugged in? On the Corsair it looks like a 4+4. On your old PSU it might have been an 8 or even a 6 pin connector.

 

[Specksan]

Yes it is plugged in. The one in my old PSU was a 4+4 too.

 

[Specksan]

Someone PLEASE help.. ive been trying to get it to work for 4 hours now checked every cable my pc just wont boot...

 

[SgtScream]

Put the old psu back into your computer and RMA the new power supply.

 

[Specksan]

Ok wtf.. I put my old PSU back in place and the same thing happened - pc didnt boot up. I'm so done. What the heck happened to my pc?!?

 

[TMTOWTSAC]

Did anything get nudged or jostled when you were swapping PSU's? Double check everything is seated properly, RAM, GPU, etc.

 

[Specksan]

Ok so apparently the POWER SW cable was hanging there and i plugged it in and boom pc boot up, this is with the old psu. I will try to put the new one in and let you know whats up later

 

[Specksan]

Yep, installed the new PSU and everything is working as it should. God i'm so relieved. 6 hours of checking and checking and it was all down to this stupid little cable

 

[TMTOWTSAC]

Power SW connects the power switch to the mobo btw. So without it, you're pressing a switch connected to nothing. Glad it wasn't anything more serious, and believe me we've all been there before.