We finally managed to plugged 4 monitors on our Tri-X R9 290X AMD Video Card after having problem connecting 4 monitors (1080p) on our R9 290X, because when you plugged 4 digital connection (not VGA), one of your monitor will automatically disabled! And if you’re using VGA adapter that is plugged on DisplayPort it will cause random flickers on your screen.
The one solution we found searching on the internet is using an Active DisplayPort adapter (non-active DisplayPort adapter will not work). So we try this adapter and indeed it works on 4 monitors without flicker issue or disabled monitors.
If you don’t have Active DisplayPort, alternative of the solution is to connect the VGA adapter on lower resolution monitor (1366×768) and flicker’s gone away.
See image below for the result. The 5th monitor are using USB to DVI..