I have Nvidia Quadro fx 580, which has a dual-link DVI port and two display ports. I was wondering if I could use two 30 inch monitors at high resolution, 2580x1600. I tried various combination, and the only one at the DVI has that resolution, and the other one at displayport has 1280x800. Any idea how I can use two 2580x1600?
Dual-mode DisplayPorts (i.e. marked with a DP++ logo) are designed to transmit a single-link DVI signal through the interface via the use of an external passive adapter that selects the desired signal. Dual-link DVI, on the other hand, requires an active adapter to convert the DisplayPort signal to the desired dual-link DVI output and does not require dual-mode DisplayPorts.
I take it that you were using a passive adapter?
Here's an example of the type of adapter you will need: