I just recieved my asus rampage IV black edition and my nvidia 780ti, heres the problem my graphics card doesnt get power but i can boot up. heres the problem i am missing a cable, i can either plug the 4 connecter in or use 2 connecters to get the 8 pin on the top board. now is this my problem cause everythingb otos up when i have the 4 connecter in im just unsure whats going on.
you need to have a proper Power Supply which can supply the needed power to the 780ti. Since your psu lacks the proper and necessary plugs i'd say you would have to start there with fixing the issue. know that when seriously overclocked some versions of the 780ti can suck up as much as 500W of power; so you'll need to make sure you have a good enough power supply moving forward.