Matrox c680 Card
Six displays
http://www.matrox.com/graphics/en/products/graphics_cards/c-series/c680/

Just a note form the user guide on this board:

Maximum resolution
4096 × 2160 @ 30 Hz
4096 × 2160 @ 60 Hz (Max. 3 monitors

So be careful if you really want to drive this card to its maximum - the refresh rates are low. And at full resolution, it only supports 3 monitors.
Jim

I bought one for the inside displays and didn't work, too slow, at the time I was using Sim-A avionics and it was a nightmare, just be careful before you buy, I can tell you that for the outside views it wouldn't work.

Cheers.

Matrox cards have for quite some time been inferior to Nvidia when it comes to flight simulation.

I was involved in a commercial installation using a similar Matrox card a couple of years ago and it worked just fine for the application it was being used. (non flight simulation)

But as the others have said, using this for a sim may not be your best choice.