I have a ATI Radeon(TM) RX 460 Graphics card, two of the slots on the back are in use as I have dual monitors in place. I have none of the default cable all screens use connectors.
1) First port is DisplayPort 1.4 ( Has connector to VGA)
2) Hdmi Port ( Has connector to VGA)
3) Dvi-D port ( Has connector to VGA)
The last port DVI-D says no signal and I cannot get the monitor to come one. Full disclosure the device I am plugging in is a huion pen display tablet, so basically a monitor you draw directly on. It works for about 1 month when I first set it up and now it just won't.
I have updated the graphics card to the latest drivers, the pen display to its latest drivers too. The computer recognizes that a pen display is plugged in bit says no signal and won't display anything.
The pen display has its own power cable, a USB connection and video output which needs to be connected to the pc, all 3 must be connected for the tablet to come on.