Now I had a similar problem the weekend with my Mars board, changed cpu from qx9650 to a 8500 and changed graphics’ card to 9800gx2. Started up no boot, fans are spinning but not the rewarding pip.

Started to strip things out, cmos etc everything I could think of, checked all the power leads, nothing I did would bring this baby back to life.

Then I pulled out PWR3 that’s the Molex by the graphic slot, and I got the pip, it booted.

I put the cable back in, fear of it being required, warm boot fine.

Switched off, switched from cold boot nothing, fans spinning, and took out the cable pwr3 whilst the fans were spinning, pip and its booting.

I have found this to be the case now,

So try this before throwing the board.

Also could some advise, why, and do you need the Molex when gx2 has 6pin and 8pin cables.
Psu Corsair 1000Hw