Mobo / Power Supply issue

I have concluded the problem is the mobo, but wanted to get your thoughts.

I have a gigabyte mobo (GA-K8NS) nforce 3. The problem stems from

when the ATX mobopower connecter is plugged on the mobo and the power cable is plugged into the psu the fans on the psu spin and the fans on the mobo spin, but i get no post codes or no screen display.

I stripped everything off the mobo, even the jumpers. The only thing connected to the mobo was the power connector.

If I take the power connector off the mobo, the fans on the psu stop.

It seems like the psu thinks the mobo is turned on. I checked any jumpers, removed the cmos. I tried diff psu's

I've concluded through process of elimination the mobo is the problem. maybe a short. I even took the mobo out the case and placed it on a box.

the computer is not supposed to start simply b/c power the power cord is plugged into the psu. I didn't even turn the power button on and the computer just began running.