I'm having issues with my first new external build. All my hardware is running but there is no post beep or signal displayed (LEDs, fans running). Which cable do I use? I already used a VGA from the monitor to the motherboard. My Windforce GTX 970 does not have a VGA slot, only 1xHDMI, 3xDisplay Port, and 2xDVI so I couldn't connect a VGA cable to it. I tried HDMI in both the motherboard and GPU but no signal displayed. I don't have a DVI cable, however. Do I need to purchase a DVI or a display port cable or no?