I have a Radeon HD7950 card, with which I'm trying to drive 3 monitors. My card has the following outputs, from right-to-left: mDP, mDP, HDMI, DVI.
I can successfully drive two DP devices and a DVI monitor (Dell U2711 via DP, Del U2717D via DP, and an older NEC 20WMGX2 via DVI). This is the working configuration:
1) DVI to NEC 20WMGX2, DP to U2711, DP to U2717D
However, when I try to replace the NEC with a second Dell U2717D, I cannot find a configuration that works. Here is what I have tried:
1) DP to U2711 (works), DP to U2717D (works), DVI-to-MDP2DVIS to U2717D (no output on this connection)
2) DP to U2711 (works), DP to U2717D (works), HDMI to U2717D (no output on this connection)
3) DVI to U2711 (no output on this connection), DP to U2717D (works), DP to U2717D (works)
I thought this would be straightforward -- I was sure configuration #3 would work as it is basically the same as what I have now, with a different set of monitors. Anyone understand why this isn't working?
I upgraded the card to an RX580 and no longer have issues driving 3 large monitors.