I also need to connect 3 monitors to my Radeon HD 5850
My Monitors are
Left and Right = Dell E193FP (VGA)
Center = Vizio E280i-A1 (VGA, HDMI, Component,)
Currently HD5850, 2 outputs DVI-I Dual Link ports are connected, 1 each to adapters and then 1 each Dell E193FP monitors. 1 output Display Adapter is hooked to an adapter (Display Port to VGA) then to Vizio E280i-A1 (VGA)
I believe that the adapters that I use do not satisfy the requirements for triple monitor
Do I have to use monitors that have the specific input without adapters?
You'll need to use a DisplayPort Active Adapter for the third display. VGA is not natively supported, so there is no guarantee it will work.