Had this same exact problem as well. Finally managed to solve it, sort of.
I put together a new mobo (the same as yours), video card (Nvidia GeForce 6600) and 2 512 sticks of ram in, pushed the power button and got the same effect. I ended up removing the vid card, one stick of ram, and my slave HDD and got it to finally run on the onboard video chip. Thing was, I had to fiddle with the RAM placement a lot to get there. I'd put a stick in slot 1, and it wouldn't work, so i put the other stick in the same slot, and it booted up no problem. Then I put the first stick back in alongside it in slot 2, and it wouldn't work. SO I took the first stick out, leaving the same configuration and placing I had when it booted correctly, and it wouldn't work. I switched them around a bit more, and finally got it to run with both in.
I know that's not much of an answer, but I'm having more problems with it even now, and I'm just going to take it back and get a decent one.
