I have 2 samsung LC27HG70QQNXZA monitors. When I connect both to the Display Ports on my Vega 64 graphics card only one display works. Yet if connect one using an HDMI port than they both work. Eventually the secondary monitor, i.e. the one connected to the HDMI port, will start to flicker. If I connect the second monitor to the HDMI port on a second graphics card they both work with no flickering. If I connect the second monitor to a display port on the second graphics card than that monitor is the only one working.
One other symptom. When I use a different monitor as my second monitor and connect using HDMI to the primary graphics both monitors work as expected.
The 2 graphics card in my computer are:
Radeon RX Vega 64, primary graphics
Radeon R9 390 Series, secondary graphics
I have tried complete removal of all AMD graphics drivers under windows safe mode and reinstalling various drivers but the problem persists.
Any ideas would be greatly appreciated!!!!