Third monitor not detected

I have a three monitor setup and am currently having issues getting my computer to detect all three monitors. I have two AMD  radeon rx 460 graphics cards. The computer is about 3 months old running Windows 10 64 bit. Two of the monitors have DVI cables, one has HDMI. Currently I can only get one of the video cards to work that has one HDMI and one DVI outlet. If I move the DVI or HDMI from the currently graphics card to the other one, the monitor is no longer detected. I have the latest graphics card drivers updated and my computer says that both graphics cards are running properly. For some reason my computer cannot detect all 3 monitors at the same time, only two at the most. And briefly when I was updating the driver for the graphics cards, I was able to use all 3 during the update. Anyone have any suggestions on how to get the third monitor detected? I've had this issue for almost a month now and am not sure what I can do differently that I haven't already tried. Thank you.