Question PC will only spin up without CPU power connected

[ap3]

Hello! new build PC with specs as follows:

CPU: i5-9600k
Mobo: MSI z390 gaming edge ac
GPU: rtx 2070 super
Psu: seasonic pulse gm650
RAM: 16gb (8x2) T series

If the CPU power is connected ev erything will spin up for 1/10th of a second then stop. without the CPU power all the fans/gpu will spin up and the MOBO will indicate it is detecting the RAM sticks in the correct places. Is the motherboard likely the issue? I have another motherboard on the way to replace this one but was hoping there is some fix that I am missing.

Thank you!

 

[thx1138v2]

Double check that you have the correct power plugs in the correct sockets.

 

[ap3]

I have done so, the 4+4 is the one I have in the CPU and the 6+2 (+6) is in my GPU. 24 pin is securely attached to mobo