I have a brand new Dell Inspiron PC. Delivering to client tomorrow. They have purchased 2 matching monitors and the necessary hardware for a twin head setup. My problem is that none of the 3 video cards I have installed work. Or, at least, they don't appear to. Without the video card in the PC, it boots the video from the motherboard just fine. When you drop in a new card, no video from any of the 3 ports (2 on card, 1 on mobo). I've done dozens of these setups in Win 7 or earlier, but I have to be missing something here in Win 8. Any ideas?