I purchased five computers configured exactly the same with Firepro w5100 cards in all of them. They all have four montiors attached (DP to DVI) and all of them work beautifully except for one. That one will only see three active monitors. I can deactivate one and the non-active monitor becomes active and can be use. But only on this one computer does it not see all four as active at the same time. All hardware is identical including monitors and cables. All are Windows 7. Any idea why this is happening or what I can do to get it to work like the others?
What specific cables are you using? I suppose you are using 3 or 4 passive DP to DVI adapters on that machine?
You need one or even two active DP to DVI adapters for your configuration.