ATX MOTHERBOARD PROBLEM

HI

I'm having problems with my ASROCK K7S41GX MoBo, when I connect the
power cord to the Power Suply unit, the computer proccessor fan turn
on, but there is no video. All the cables inside the mobo are
disconnected (hd, cd, floppy), only the ones of the frontal panel are
connected.
The problem begins when the power cord was unplugged while the machine
was on.

Here is what I've tried:

- Use the PSU in another Mobo and it works fine
- Use the PSU of another PC in my Mobo and don't work. The same
situation that I expose above.
- Short cut the pins 14 - 15 (PS_ON) of the PSU... Don't work, the
same simptoms.
- Short cut the ClearCMOS in the Mobo. Don't work.

My question...

It's possible that my mobo has a jumper setting that is making it
always be with power on???
Is there a way to Short cut the power pins in the Mobo to
reinicializate the settings of my mobo??

Please Help...