Help with psu swap

[bjandthebeans]

I've replaced a faulty PSU with another similar HEC 550W unit. Reconnected all leads as per my disconnection notes but I can't activate my PC. A green LED at the bottom of my Mobo indicates power but the LED is normally a steady illumination - the LED display is flashing. I have a slight doubt re connection of my 4pin+20pin multiconnector to the mobo as there is a cores colour discrepancy at the 4 pin end at the top of the connector - I've noted yellow cores at the top but the cores are orange. Can anyone confirm what core colours are at the top what are the normal core cvolours at the bottom of the 20 pin connector? My mobo is an ASUS P5N32 SLI de luxe.
Any useful advice appreciated.

[bjandthebeans]

Additional: The cable core colours on my top 4 pin connector, plugged to the mobo, are orange (left side) and black (right side), yellow below orange, red below black. On the 20 pin connector, located below the 4 pin one, the top 2 cores are yellow and red, the bottom 2 x cores are orange. I'm assuming a standard cable core colour allocations on the mobo connector but can any user confirm this?