Hello,
You have the connectors swapped for the Power Supply side and PCB side.
These two connectors need to be swapped.
24 pin MOLEX 39-01-2240 connector at the motherboard. (to Power Supply)
24 pin MOLEX 44206-0007 or equivalent connector at the PSU cable. (to PCB)
Everything else seems fine so far.
Updated.
Thank you.