So I've noticed that my Hd2600Xt is not really that fast so i bought an Nvidia 9800GT. I opened my mac pro, took out my old GfxCard, and put in the new one. But the 9800 needs a secondary power supply. Now, i have a 6pin -> 4pin cable: . I've connected the 6 pin part into the graphics card But i don't know where to put the 4 pin!!!! HELP PLEASE!!!!