Your not making any sense. You video card is powered by the motherboard, you don't plug it into anything else.
Even I'm confused, all I know is that my PSU is some weird brand that does weird things. With the old cable power cable that I had plugged into the dvd drive, the dvd drive would not work as long as the graphics card was installed. As soon as I removed it the dvd drive worked. Now I realised I had a spare SATA power connector lying around(it's supposedly coming out from the same set of wires that has another sata power cable that's plugged into my hard drive) by plugging this spare cable into my dvd drive, my dvd drive works fine even though my graphics card is installed.