Recently I reinstalled Windows 10 on my desktop pc:
Drive 250GB SSD
Graphics cards 2x (AMD) Sapphire Radeon HD7950
Processor AMD FX(tm)-8350 4.00GHz (8 cores)
Main board AsRock 970 Extreme 3
Long before doing so, 3 screens were properly connected (without using active displayport, by connecting two screens to the upper card using DVI-I and DVI-D, and the remaining screen using DVI-I to the lower one), and the desktop was extended to each display. One day, all of the sudden the screens went black and only two went back on. It might have been due to an automatic update of the graphics drivers?
The weird thing is, during the (re/de)installation of the latest Crimson Relive (which I assume it the proper driver), all of the screens go black a few times, but once or twice they all show. At the end of the installation, however, only two remain. This appears to concern to which graphics card the screens are connected. Whatever the port used to connect a screen when trying to connect it to the lower card (the one that's in the second PCI-e slot), the screen does not receive a signal. This has been confirmed for any type of connection (i.e. DVI-I, DVI-D, VGA, HDMI and DisplayPort). The cards are linked by means of Crossfire.
What to do?