New ASrock Z77 Pro3 upgrade and PC boots when AC power connected

[raybo1]

I have just upgraded a Dell XPS 630 including replacing the stock motherboard with an ASrock Z77 Pro3.
As soon as I plug in the AC power cable, the PC boots - without using the powerbutton. When I try to turn it off using the normal Start-Shutdown sequence it powers down normally, shuts down (no noise from fans/drives) and then a couple of seconds later boots up again.
Does anybody have any suggestions on what could be causing this problem ?

Everything else appears to be running fine. I'd appreciate any help.

 

[alexoiu]

I guess that the reset and/or power button wires are not correctly connected to the motherboard. Check the manual for the front panel connector pinout.

 

[raybo1]

I guess that the reset and/or power button wires are not correctly connected to the motherboard. Check the manual for the front panel connector pinout.

Thanks for advice.
This is far from my area of expertise - window installation (the ones with glass)
Would you mind looking at the attached pinout diagrams and telling me if I need to rearrange the pins and if so where.
XPS

ASrock