I think I may have found the problem - as I was taking everything out of my case - when I unplugged the MAIN power supply wire that goes from my PSU to my mobo (the 20+4) wire... the 4 wire was fine .. and so was 19 out of the 20 holes on the wire of my PSU - but one hole was empty ... do you think this is the reason for the lack of power??
The missing pin is #10 (+12V) ... that sounds important.
EDIT : Nvm, I wasn't looking at the pin alignment close enough and I had it backwards, the missing pin is #17 - which is GND - so that should not matter right?