Having More Than One Dedicated Graphics Card Is Called SLI. In Order To SLI You Would Need An SLI Bridge And Another GTX 760( Same Card You Have) You Cant SLI Two Different Cards. Secondly , You Would Need To See If Your Motherboard Supports That. Thirdly, Make Sure You Dont Have A Chineese PSU, Or Else It Could Lead To Death In Other Components.