Install BoosterX5 GPU Power

I got a sweet GTX 580 for my Mac Pro to run CS 6, Davinci etc. I know that it needs additional power, so I bought the Booster X 5.

Other than figuring out a way to jam it in there and run the power cables, I've run into an issue that has me stopped. The X5 has a 4 pin molex connector in order to tell it when to turn on and off (it doesn't draw power).

But, the Mac pro doesn't have any 4 pin connector in the drive bay. It has the SATA one, but I can't find an adapter.

Furthermore, I don't know where else to draw power from to even make my own cable if I had to.

Please help.

Thanks