I have 3 NEC LCD2690WUXI monitors and a Radeon HD 7900 card
One Monitor on DVI-D
and 2 monitors plugged into the Mini Display port via Accell B087B-006B active adapters
My problem is when plugging in the second Mini Display adapted monitor all monitors starting flickering on and off (with the decive added sound going on and off) until you unplug one of the Mini Display adapted monitors. It dose not matter if all 3 are plugged in or just the two Mini Display adapted monitors all monitors connected start flinkering on and off until you pull the plug on of the mini display ports.
All monitors have the same settings.
Both monitors work on the Mini dispolay port when only one is plugged in.