Hard drive won’t turn on when IDE cable Inserted

Just got a new mobo, chip, HD, Pwr. S. When I plug both IDE and Pwr in the new Seagate 320g HD, it won’t turn on. With IDE out, it powers up just fine. I swapped to another IDE cable, and the same thing happened. I used another HD from my other pc, and It does the same thing. I tried both cables, same thing. If two hard drives and two cables all behave the same way, I don’t think its either of them. It gets stranger. I have two DVD burners in the machine. If they have both IDE and PWR cables in them, a green light turns on the DVD drives, but they will not open. If I take out the IDE, the light comes on, I can open them no problem. So, all drives, both cables, no worky worky. I am completly at a loss as to what is causing this. Mobo>?