I should have included this in my original post...
The PS is a "known to be good" Aspire ATX-AS520W 12V.
The 12V lead is connected to the m-board.
The m-board uses a 20-pin power connector.
One of the Molex connectors IS connected to the graphics card.

If there is any other way I can help, so someone is able to help me, please let me know.

Thanks again, DamJ